Gavin Newsom, the perpetually preened California governor with national ambitions, is in a tough spot as the person empowered to temporarily fill Dianne Feinstein’s seat if the 89-year-old senator, who is currently fighting a bout of shingles, succumbs to mounting pressure to retire. First, there is the problem of Senate procedure: Feinstein’s absence has been holding up critical judicial appointments. She has asked Chuck Schumer to replace her while she’s unable to travel, but that would require the unanimous consent of the Senate to avoid procedural issues—a quixotic fantasy in this day and age.

Second, and more troublesome for Newsom, is the intra-state political tensions that Feinstein’s resignation would unleash. Newsom, after all, would have to choose between three crucial voting blocs while simultaneously weighing their impact on his own political future. He has already promised to appoint a Black woman to the post if Feinstein were to resign early, which would presumably tip the scales for Rep. Barbara Lee. But Lee has already announced her intentions to compete in the primary for Feinstein’s seat; simply giving her the appointment would be an obvious advantage that would deeply anger Rep. Adam Schiff, who announced his own Senate campaign back in January, and who shares a number of donors, consultants and supporters with Newsom. Nevertheless, the Congressional Black Caucus is bearing down on Newsom to follow through on his promise, and they represent an influential bloc that he would need if—or when—he runs for president. (Rep. Katie Porter is surely the least likely to get the shoulder tap from Newsom, even if passing her over pisses off her progressive fan base; Feinstein’s people are still livid that she dared to announce her candidacy without consulting her first, and Feinstein wants a say in her successor. Plus, Feinstein and Nancy Pelosi privately prefer Schiff.)