Joe Biden’s team is considering an informal ban on naming Democratic U.S. senators to the Cabinet if he wins — which would effectively block Elizabeth Warren for Treasury or Bernie Sanders for Labor — people familiar with the discussions tell Axios.

The big picture: Biden, if he wins, is bracing for bruising legislative battles on day one, starting with the next phase of coronavirus relief. Many advisers don’t think he can afford to lose a single vote in the Senate if Democrats hold a slim majority.

Biden himself hasn’t made a decision on a potential Senate ban, with his efforts focused on winning on Tuesday, the sources say.

The intrigue: An informal ban could also be an elegant way of tamping down campaigns to place progressive senators in top Cabinet roles by reminding the movement of the priority around enacting legislation.