Tom Steyer is supposedly a candidate for president. But he is spending much of his time at home in California. 

Yes, he’s made trips to Iowa and New Hampshire, but he resembles a statewide candidate in California. It’s not just his schedule of events, most recently a climate change event in Oakland. His team is heavily Californian. And his policy prescriptions mirror the priorities of California.

In this context, it’s fair to wonder what his real goal is. He has never held elected office, so starting out as president seems both improbable and, as the current occupant of the White House shows, dangerous. Steyer’s late entry into the presidential race suggests he wasn’t sure about being president. And he stays in the race even though his support was too small to make the September debate. Steyer isn’t going to be president. So what is he really running for?

My guess is: U.S. Senator.

There’s a decent chance that a U.S Senate seat opens up in the next couple years. Dianne Feinstein is the oldest member of the U.S Senate, and if you  believe the actuarial tables, it’s no better than a 50-50 chance that she finishes her current term. And a seat could open up if Kamala Harris ends up being the next president or vice president.

Steyer’s California-focused presidential campaign thus feels like an enterprise designed to make him a favorite for a Senate seat. He can build his contacts and raise money and, above all, build his profile and name recognition. Then, he’ll be ready to take over for Feinstein or Harris when the seats open up—either by winning an appointment from Gov. Gavin Newsom, or winning a special election to replace either one.