diff --git a/src/heretic/main.py b/src/heretic/main.py
index 016c3920..5c4747a5 100644
--- a/src/heretic/main.py
+++ b/src/heretic/main.py
@@ -10,6 +10,7 @@
 from importlib.metadata import version
 from os.path import commonprefix
 from pathlib import Path
+from typing import Any
 
 import huggingface_hub
 import optuna
@@ -171,6 +172,12 @@ def run():
         )
         return
 
+    # Keep Hugging Face credentials in memory for this process only.
+    # We don't use huggingface_hub.login() because that stores the token on disk.
+    # Since this program will often be run on rented or shared GPU servers,
+    # it is better to not persist credentials.
+    hf_token = huggingface_hub.get_token()
+
     # Adapted from https://github.com/huggingface/accelerate/blob/main/src/accelerate/commands/env.py
     if torch.cuda.is_available():
         count = torch.cuda.device_count()
@@ -598,6 +605,48 @@ def count_completed_trials() -> int:
     if count_completed_trials() == settings.n_trials:
         study.set_user_attr("finished", True)
 
+    def print_hf_user_info(user: dict[str, Any]) -> None:
+        fullname = user.get(
+            "fullname",
+            user.get("name", "unknown user"),
+        )
+        email = user.get("email", "no email found")
+        print(f"Logged in as [bold]{fullname} ({email})[/]")
+
+    def validate_hf_token(t: str) -> dict[str, Any] | None:
+        try:
+            user = huggingface_hub.whoami(t)
+            print_hf_user_info(user)
+            return user
+        except huggingface_hub.errors.HfHubHTTPError as error:
+            print(f"[red]Failed to validate the Hugging Face token: ({error})[/]")
+            return None
+
+    def authenticate_hf(token: str | None) -> tuple[dict[str, Any], str]:
+        # Try to use an existing token (from env, hf auth login, or a previous upload).
+        if token:
+            user = validate_hf_token(token)
+            if user:
+                choice = prompt_select(
+                    "How do you want to proceed?",
+                    ["Use this account", "Switch account"],
+                )
+                if choice is None:
+                    raise KeyboardInterrupt
+                if choice == "Use this account":
+                    return user, token
+                # User chose "Switch account"; fall through to prompt for new token.
+
+        # No valid token yet (first time, switch account, or validation failed).
+        # Prompt for a token until we get a valid one or the user cancels.
+        while True:
+            new_token = prompt_password("Hugging Face access token:")
+            if new_token is None:
+                raise KeyboardInterrupt
+            user = validate_hf_token(new_token)
+            if user:
+                return user, new_token
+
     while True:
         # If no trials at all have been evaluated, the study must have been stopped
         # by pressing Ctrl+C while the first trial was running. In this case, we just
@@ -765,23 +814,11 @@ def count_completed_trials() -> int:
                             print(f"Model saved to [bold]{save_directory}[/].")
 
                         case "Upload the model to Hugging Face":
-                            # We don't use huggingface_hub.login() because that stores the token on disk,
-                            # and since this program will often be run on rented or shared GPU servers,
-                            # it's better to not persist credentials.
-                            token = huggingface_hub.get_token()
-                            if not token:
-                                token = prompt_password("Hugging Face access token:")
-                            if not token:
+                            try:
+                                user, hf_token = authenticate_hf(hf_token)
+                            except KeyboardInterrupt:
                                 continue
 
-                            user = huggingface_hub.whoami(token)
-                            fullname = user.get(
-                                "fullname",
-                                user.get("name", "unknown user"),
-                            )
-                            email = user.get("email", "no email found")
-                            print(f"Logged in as [bold]{fullname} ({email})[/]")
-
                             repo_id = prompt_text(
                                 "Name of repository:",
                                 default=f"{user['name']}/{Path(settings.model).name}-heretic",
@@ -805,7 +842,7 @@ def count_completed_trials() -> int:
                                 model.model.push_to_hub(
                                     repo_id,
                                     private=private,
-                                    token=token,
+                                    token=hf_token,
                                 )
                             else:
                                 print("Uploading merged model...")
@@ -813,14 +850,14 @@ def count_completed_trials() -> int:
                                 merged_model.push_to_hub(
                                     repo_id,
                                     private=private,
-                                    token=token,
+                                    token=hf_token,
                                 )
                                 del merged_model
                                 empty_cache()
                                 model.tokenizer.push_to_hub(
                                     repo_id,
                                     private=private,
-                                    token=token,
+                                    token=hf_token,
                                 )
 
                             # If the model path exists locally and includes the
@@ -857,7 +894,7 @@ def count_completed_trials() -> int:
                                     )
                                     + card.text
                                 )
-                                card.push_to_hub(repo_id, token=token)
+                                card.push_to_hub(repo_id, token=hf_token)
 
                             print(f"Model uploaded to [bold]{repo_id}[/].")
 
diff --git a/src/heretic/utils.py b/src/heretic/utils.py
index a0d5f35f..41d9f0f9 100644
--- a/src/heretic/utils.py
+++ b/src/heretic/utils.py
@@ -133,7 +133,7 @@ def prompt_path(message: str) -> str:
         return questionary.path(message, only_directories=True).ask()
 
 
-def prompt_password(message: str) -> str:
+def prompt_password(message: str) -> str | None:
     if is_notebook():
         print()
         return getpass.getpass(message)