diff --git a/src/djangooidc/views.py b/src/djangooidc/views.py
index c4d4cec81..815df4ecf 100644
--- a/src/djangooidc/views.py
+++ b/src/djangooidc/views.py
@@ -9,8 +9,6 @@ from django.http import HttpResponseRedirect
 from django.shortcuts import redirect
 from urllib.parse import parse_qs, urlencode
 
-from waffle import flag_is_active
-
 from djangooidc.oidc import Client
 from djangooidc import exceptions as o_e
 from registrar.models import User
@@ -113,13 +111,6 @@ def login_callback(request):
             if not user.verification_type or is_fixture_user:
                 user.set_user_verification_type()
                 user.save()
-            
-            if not flag_is_active(request, "multiple_portfolios"):
-                user.set_default_last_selected_portfolio()
-                user.save()
-            else: 
-                user.last_selected_portfolio = None
-                user.save()
 
             login(request, user)
             logger.info("Successfully logged in user %s" % user)
diff --git a/src/registrar/admin.py b/src/registrar/admin.py
index fd555520d..a41035f71 100644
--- a/src/registrar/admin.py
+++ b/src/registrar/admin.py
@@ -717,17 +717,12 @@ class MyUserAdmin(BaseUserAdmin, ImportExportModelAdmin):
                     "is_superuser",
                     "groups",
                     "user_permissions",
-                    "last_selected_portfolio",
                 )
             },
         ),
         ("Important dates", {"fields": ("last_login", "date_joined")}),
     )
 
-    autocomplete_fields = [
-        "last_selected_portfolio",
-    ]
-
     readonly_fields = ("verification_type",)
 
     analyst_fieldsets = (
@@ -747,7 +742,6 @@ class MyUserAdmin(BaseUserAdmin, ImportExportModelAdmin):
                 "fields": (
                     "is_active",
                     "groups",
-                    "last_selected_portfolio",
                 )
             },
         ),
@@ -802,7 +796,6 @@ class MyUserAdmin(BaseUserAdmin, ImportExportModelAdmin):
         "Important dates",
         "last_login",
         "date_joined",
-        "last_selected_portfolio",
     ]
 
     # TODO: delete after we merge organization feature
diff --git a/src/registrar/context_processors.py b/src/registrar/context_processors.py
index ca7c92892..7d28260ed 100644
--- a/src/registrar/context_processors.py
+++ b/src/registrar/context_processors.py
@@ -61,27 +61,34 @@ def add_has_profile_feature_flag_to_context(request):
 def portfolio_permissions(request):
     """Make portfolio permissions for the request user available in global context"""
     try:
-        if not request.user or not request.user.is_authenticated or not flag_is_active(request, "organization_feature"):
+        if request.session["portfolio"] is not None:
             return {
-                "has_base_portfolio_permission": False,
-                "has_domains_portfolio_permission": False,
-                "has_domain_requests_portfolio_permission": False,
-                "portfolio": None,
-                "has_organization_feature_flag": False,
+                "has_base_portfolio_permission": request.user.has_base_portfolio_permission(request.session["portfolio"]),
+                "has_domains_portfolio_permission": request.user.has_domains_portfolio_permission(request.session["portfolio"]),
+                "has_domain_requests_portfolio_permission": request.user.has_domain_requests_portfolio_permission(request.session["portfolio"]),
+                "has_view_suborganization": request.user.has_view_suborganization(request.session["portfolio"]),
+                "has_edit_suborganization": request.user.has_edit_suborganization(request.session["portfolio"]),
+                "portfolio": request.session["portfolio"],
+                "has_organization_feature_flag": True,
             }
         return {
-            "has_base_portfolio_permission": request.user.has_base_portfolio_permission(),
-            "has_domains_portfolio_permission": request.user.has_domains_portfolio_permission(),
-            "has_domain_requests_portfolio_permission": request.user.has_domain_requests_portfolio_permission(),
-            "portfolio": request.user.last_selected_portfolio,
-            "has_organization_feature_flag": True,
+            "has_base_portfolio_permission": False,
+            "has_domains_portfolio_permission": False,
+            "has_domain_requests_portfolio_permission": False,
+            "has_view_suborganization": False,
+            "has_edit_suborganization": False,
+            "portfolio": None,
+            "has_organization_feature_flag": False,
         }
+        
     except AttributeError:
         # Handles cases where request.user might not exist
         return {
             "has_base_portfolio_permission": False,
             "has_domains_portfolio_permission": False,
             "has_domain_requests_portfolio_permission": False,
+            "has_view_suborganization": False,
+            "has_edit_suborganization": False,
             "portfolio": None,
             "has_organization_feature_flag": False,
         }
diff --git a/src/registrar/migrations/0119_remove_user_portfolio_and_more.py b/src/registrar/migrations/0119_remove_user_portfolio_and_more.py
index 7c9d2defc..84ed45cd1 100644
--- a/src/registrar/migrations/0119_remove_user_portfolio_and_more.py
+++ b/src/registrar/migrations/0119_remove_user_portfolio_and_more.py
@@ -25,17 +25,6 @@ class Migration(migrations.Migration):
             model_name="user",
             name="portfolio_roles",
         ),
-        migrations.AddField(
-            model_name="user",
-            name="last_selected_portfolio",
-            field=models.ForeignKey(
-                blank=True,
-                null=True,
-                on_delete=django.db.models.deletion.SET_NULL,
-                related_name="portfolio_selected_by_users",
-                to="registrar.portfolio",
-            ),
-        ),
         migrations.CreateModel(
             name="UserPortfolioPermission",
             fields=[
diff --git a/src/registrar/models/user.py b/src/registrar/models/user.py
index 34f2f8bcf..b151f3800 100644
--- a/src/registrar/models/user.py
+++ b/src/registrar/models/user.py
@@ -110,14 +110,6 @@ class User(AbstractUser):
         related_name="users",
     )
 
-    last_selected_portfolio = models.ForeignKey(
-        "registrar.Portfolio",
-        null=True,
-        blank=True,
-        related_name="portfolio_selected_by_users",
-        on_delete=models.SET_NULL,
-    )
-
     phone = PhoneNumberField(
         null=True,
         blank=True,
@@ -208,50 +200,48 @@ class User(AbstractUser):
     def has_contact_info(self):
         return bool(self.title or self.email or self.phone)
 
-    def _has_portfolio_permission(self, portfolio_permission):
+    def _has_portfolio_permission(self, portfolio, portfolio_permission):
         """The views should only call this function when testing for perms and not rely on roles."""
 
-        if not self.last_selected_portfolio:
-            return False
-
-        portfolio_perms = self.portfolio_permissions.filter(portfolio=self.last_selected_portfolio, user=self).first()
+        portfolio_perms = self.portfolio_permissions.filter(portfolio=portfolio, user=self).first()
         if not portfolio_perms:
             return False
 
         portfolio_permissions = portfolio_perms._get_portfolio_permissions()
         return portfolio_permission in portfolio_permissions
 
-    def has_base_portfolio_permission(self):
-        return self._has_portfolio_permission(UserPortfolioPermissionChoices.VIEW_PORTFOLIO)
+    def has_base_portfolio_permission(self, portfolio):
+        return self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.VIEW_PORTFOLIO)
 
-    def has_edit_org_portfolio_permission(self):
-        return self._has_portfolio_permission(UserPortfolioPermissionChoices.EDIT_PORTFOLIO)
+    def has_edit_org_portfolio_permission(self, portfolio):
+        return self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.EDIT_PORTFOLIO)
 
-    def has_domains_portfolio_permission(self):
-        return self._has_portfolio_permission(
+    def has_domains_portfolio_permission(self, portfolio):
+        return self._has_portfolio_permission(portfolio,
             UserPortfolioPermissionChoices.VIEW_ALL_DOMAINS
-        ) or self._has_portfolio_permission(UserPortfolioPermissionChoices.VIEW_MANAGED_DOMAINS)
+        ) or self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.VIEW_MANAGED_DOMAINS)
 
-    def has_domain_requests_portfolio_permission(self):
-        return self._has_portfolio_permission(
+    def has_domain_requests_portfolio_permission(self, portfolio):
+        return self._has_portfolio_permission(portfolio,
             UserPortfolioPermissionChoices.VIEW_ALL_REQUESTS
-        ) or self._has_portfolio_permission(UserPortfolioPermissionChoices.VIEW_CREATED_REQUESTS)
+        ) or self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.VIEW_CREATED_REQUESTS)
 
-    def has_view_all_domains_permission(self):
+    def has_view_all_domains_permission(self, portfolio):
         """Determines if the current user can view all available domains in a given portfolio"""
-        return self._has_portfolio_permission(UserPortfolioPermissionChoices.VIEW_ALL_DOMAINS)
+        return self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.VIEW_ALL_DOMAINS)
 
     # Field specific permission checks
-    def has_view_suborganization(self):
-        return self._has_portfolio_permission(UserPortfolioPermissionChoices.VIEW_SUBORGANIZATION)
+    def has_view_suborganization(self, portfolio):
+        return self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.VIEW_SUBORGANIZATION)
 
-    def has_edit_suborganization(self):
-        return self._has_portfolio_permission(UserPortfolioPermissionChoices.EDIT_SUBORGANIZATION)
+    def has_edit_suborganization(self, portfolio):
+        return self._has_portfolio_permission(portfolio, UserPortfolioPermissionChoices.EDIT_SUBORGANIZATION)
 
-    def set_default_last_selected_portfolio(self):
+    def get_first_portfolio(self):
         permission = self.portfolio_permissions.first()
         if permission:
-            self.last_selected_portfolio = permission.portfolio
+            return permission.portfolio
+        return None
 
     @classmethod
     def needs_identity_verification(cls, email, uuid):
@@ -367,7 +357,7 @@ class User(AbstractUser):
             email__iexact=self.email, status=PortfolioInvitation.PortfolioInvitationStatus.INVITED
         ):
             only_single_portfolio = (
-                not flag_is_active(None, "multiple_portfolios") and self.last_selected_portfolio is None
+                not flag_is_active(None, "multiple_portfolios") and self.get_first_portfolio() is None
             )
             if only_single_portfolio or flag_is_active(None, "multiple_portfolios"):
                 try:
@@ -396,12 +386,12 @@ class User(AbstractUser):
 
     def is_org_user(self, request):
         has_organization_feature_flag = flag_is_active(request, "organization_feature")
-        return has_organization_feature_flag and self.has_base_portfolio_permission()
+        return has_organization_feature_flag and self.has_base_portfolio_permission(request.session["portfolio"])
 
     def get_user_domain_ids(self, request):
         """Returns either the domains ids associated with this user on UserDomainRole or Portfolio"""
-        if self.is_org_user(request) and self.has_view_all_domains_permission():
-            return DomainInformation.objects.filter(portfolio=self.last_selected_portfolio).values_list(
+        if self.is_org_user(request) and self.has_view_all_domains_permission(request.session["portfolio"]):
+            return DomainInformation.objects.filter(portfolio=request.session["portfolio"]).values_list(
                 "domain_id", flat=True
             )
         else:
diff --git a/src/registrar/registrar_middleware.py b/src/registrar/registrar_middleware.py
index 6e7d110fb..1da74a527 100644
--- a/src/registrar/registrar_middleware.py
+++ b/src/registrar/registrar_middleware.py
@@ -125,8 +125,9 @@ class CheckUserProfileMiddleware:
 
 class CheckPortfolioMiddleware:
     """
-    Checks if the current user has a portfolio
-    If they do, redirect them to the portfolio homepage when they navigate to home.
+    this middleware should serve two purposes:
+      1 - set the portfolio in session if appropriate   # views will need the session portfolio
+      2 - if path is home and session portfolio is set, redirect based on permissions of user
     """
 
     def __init__(self, get_response):
@@ -140,20 +141,28 @@ class CheckPortfolioMiddleware:
     def process_view(self, request, view_func, view_args, view_kwargs):
         current_path = request.path
 
-        if current_path == self.home and request.user.is_authenticated and request.user.is_org_user(request):
+        if not request.user.is_authenticated:
+            return None
+        
+        # set the portfolio in the session if it is not set
+        if not "portfolio" in request.session or request.session["portfolio"] is None:
+            # if user is a multiple portfolio
+            if flag_is_active(request, "multiple_portfolios"):
+                # NOTE: we will want to change later to have a workflow for selecting
+                # portfolio and another for switching portfolio; for now, select first
+                request.session["portfolio"] = request.user.get_first_portfolio()
+            elif flag_is_active(request, "organization_feature"):            
+                request.session["portfolio"] = request.user.get_first_portfolio()
+            else:
+                request.session["portfolio"] = None
 
-            if request.user.has_base_portfolio_permission():
-                portfolio = request.user.last_selected_portfolio
-
-                # Add the portfolio to the request object
-                request.last_selected_portfolio = portfolio
-
-                if request.user.has_domains_portfolio_permission():
+        if request.session["portfolio"] is not None and current_path == self.home:  
+            if request.user.has_base_portfolio_permission(request.session["portfolio"]):
+                if request.user.has_domains_portfolio_permission(request.session["portfolio"]):
                     portfolio_redirect = reverse("domains")
                 else:
                     # View organization is the lowest access
                     portfolio_redirect = reverse("organization")
-
                 return HttpResponseRedirect(portfolio_redirect)
 
         return None
diff --git a/src/registrar/templates/domain_detail.html b/src/registrar/templates/domain_detail.html
index 19f196e40..cf55f7070 100644
--- a/src/registrar/templates/domain_detail.html
+++ b/src/registrar/templates/domain_detail.html
@@ -72,7 +72,7 @@
       {% include "includes/summary_item.html" with title='DNSSEC' value='Not Enabled' edit_link=url editable=is_editable %}
     {% endif %}
 
-    {% if portfolio and has_domains_portfolio_permission and request.user.has_view_suborganization %}
+    {% if portfolio and has_domains_portfolio_permission and has_view_suborganization %}
       {% url 'domain-suborganization' pk=domain.id as url %}
       {% include "includes/summary_item.html" with title='Suborganization' value=domain.domain_info.sub_organization edit_link=url editable=is_editable|and:request.user.has_edit_suborganization %}
     {% else %}
diff --git a/src/registrar/templates/domain_sidebar.html b/src/registrar/templates/domain_sidebar.html
index f2e9f190c..24f92bf16 100644
--- a/src/registrar/templates/domain_sidebar.html
+++ b/src/registrar/templates/domain_sidebar.html
@@ -61,7 +61,7 @@
       
       {% if portfolio %}
           {% comment %} Only show this menu option if the user has the perms to do so {% endcomment %}
-          {% if has_domains_portfolio_permission and request.user.has_view_suborganization %}
+          {% if has_domains_portfolio_permission and has_view_suborganization %}
             {% with url_name="domain-suborganization" %}
               {% include "includes/domain_sidenav_item.html" with item_text="Suborganization" %}
             {% endwith %}
diff --git a/src/registrar/templates/includes/domains_table.html b/src/registrar/templates/includes/domains_table.html
index 73331c3f0..f790da4d5 100644
--- a/src/registrar/templates/includes/domains_table.html
+++ b/src/registrar/templates/includes/domains_table.html
@@ -157,7 +157,7 @@
             <th data-sortable="name" scope="col" role="columnheader">Domain name</th>
             <th data-sortable="expiration_date" scope="col" role="columnheader">Expires</th>
             <th data-sortable="state_display" scope="col" role="columnheader">Status</th>
-            {% if has_domains_portfolio_permission and request.user.has_view_suborganization %}
+            {% if has_domains_portfolio_permission and has_view_suborganization %}
               <th data-sortable="suborganization" scope="col" role="columnheader">Suborganization</th>
             {% endif %}
             <th 
diff --git a/src/registrar/views/domain.py b/src/registrar/views/domain.py
index bd3392c69..d6ffbf64a 100644
--- a/src/registrar/views/domain.py
+++ b/src/registrar/views/domain.py
@@ -177,7 +177,7 @@ class DomainView(DomainBaseView):
         if self.request.user.has_domains_portfolio_permission():
             if Domain.objects.filter(id=pk).exists():
                 domain = Domain.objects.get(id=pk)
-                if domain.domain_info.portfolio == self.request.user.last_selected_portfolio:
+                if domain.domain_info.portfolio == self.request.session["portfolio"]:
                     return True
         return False
 
@@ -236,7 +236,7 @@ class DomainOrgNameAddressView(DomainFormBaseView):
 
         # Org users shouldn't have access to this page
         is_org_user = self.request.user.is_org_user(self.request)
-        if self.request.user.last_selected_portfolio and is_org_user:
+        if self.request.session["portfolio"] and is_org_user:
             return False
         else:
             return super().has_permission()
@@ -255,7 +255,7 @@ class DomainSubOrganizationView(DomainFormBaseView):
 
         # non-org users shouldn't have access to this page
         is_org_user = self.request.user.is_org_user(self.request)
-        if self.request.user.last_selected_portfolio and is_org_user:
+        if self.request.session["portfolio"] and is_org_user:
             return super().has_permission()
         else:
             return False
@@ -335,7 +335,7 @@ class DomainSeniorOfficialView(DomainFormBaseView):
 
         # Org users shouldn't have access to this page
         is_org_user = self.request.user.is_org_user(self.request)
-        if self.request.user.last_selected_portfolio and is_org_user:
+        if self.request.session["portfolio"] and is_org_user:
             return False
         else:
             return super().has_permission()
diff --git a/src/registrar/views/portfolios.py b/src/registrar/views/portfolios.py
index 81c104790..554576a2e 100644
--- a/src/registrar/views/portfolios.py
+++ b/src/registrar/views/portfolios.py
@@ -51,15 +51,14 @@ class PortfolioOrganizationView(PortfolioBasePermissionView, FormMixin):
     def get_context_data(self, **kwargs):
         """Add additional context data to the template."""
         context = super().get_context_data(**kwargs)
-        context["has_edit_org_portfolio_permission"] = self.request.user.has_edit_org_portfolio_permission()
+        context["has_edit_org_portfolio_permission"] = self.request.user.has_edit_org_portfolio_permission(self.request.session["portfolio"])
         return context
 
     def get_object(self, queryset=None):
-        """Get the portfolio object based on the request user."""
-        portfolio = self.request.user.last_selected_portfolio
-        if portfolio is None:
+        """Get the portfolio object based on the session."""
+        if self.request.session["portfolio"] is None:
             raise Http404("No organization found for this user")
-        return portfolio
+        return self.request.session["portfolio"]
 
     def get_form_kwargs(self):
         """Include the instance in the form kwargs."""
@@ -111,11 +110,10 @@ class PortfolioSeniorOfficialView(PortfolioBasePermissionView, FormMixin):
     context_object_name = "portfolio"
 
     def get_object(self, queryset=None):
-        """Get the portfolio object based on the request user."""
-        portfolio = self.request.user.last_selected_portfolio
-        if portfolio is None:
+        """Get the portfolio object based on the session."""
+        if self.request.session["portfolio"] is None:
             raise Http404("No organization found for this user")
-        return portfolio
+        return self.request.session["portfolio"]
 
     def get_form_kwargs(self):
         """Include the instance in the form kwargs."""
diff --git a/src/registrar/views/utility/mixins.py b/src/registrar/views/utility/mixins.py
index 16a896100..c6fdd5b0a 100644
--- a/src/registrar/views/utility/mixins.py
+++ b/src/registrar/views/utility/mixins.py
@@ -419,7 +419,7 @@ class PortfolioBasePermission(PermissionsLoginMixin):
         if not self.request.user.is_authenticated:
             return False
 
-        return self.request.user.has_base_portfolio_permission()
+        return self.request.user.has_base_portfolio_permission(self.request.session["portfolio"])
 
 
 class PortfolioDomainsPermission(PortfolioBasePermission):
@@ -434,7 +434,7 @@ class PortfolioDomainsPermission(PortfolioBasePermission):
 
         if not self.request.user.is_authenticated:
             return False
-        return self.request.user.has_domains_portfolio_permission()
+        return self.request.user.has_domains_portfolio_permission(self.request.session["portfolio"])
 
 
 class PortfolioDomainRequestsPermission(PortfolioBasePermission):
@@ -449,4 +449,4 @@ class PortfolioDomainRequestsPermission(PortfolioBasePermission):
 
         if not self.request.user.is_authenticated:
             return False
-        return self.request.user.has_domain_requests_portfolio_permission()
+        return self.request.user.has_domain_requests_portfolio_permission(self.request.session["portfolio"])