Their logic: If Warren, a Democrat, wins Sen. Scott Brown’s (R-Mass.) seat and President Obama wins reelection — and then appoints Kerry to his Cabinet — that would leave Brown the favorite to take Kerry’s Senate seat in a special election.

And whether or not Democrats keep their Senate majority come November, the upper chamber will be narrowly divided next year — perhaps a 50-50 split. Plus, Democratic leaders face another daunting electoral map in the 2014 election cycle, when they will have to defend 20 seats, compared to only 13 up for reelection in the GOP column.

That could leave Obama unlikely to risk a safe Democratic seat to fill the job of Secretary of State Hillary Clinton, who has said she’ll leave Foggy Bottom early next year.