With early voting in the California primary now underway, and more Californians set to head to the polls in less than three weeks to cast their ballots, the tumultuous race to replace Gov. Gavin Newsom is still rife with uncertainty.

The top two vote-getters in the primary, regardless of their party affiliation, will advance to the general election in November. And the race for those two spots looks very different now than it did just a month ago.

Earlier this year, then-Rep. Eric Swalwell was the frontrunner among the crowded field of Democrats. But he ended his campaign and resigned from Congress in April, following several reported allegations of sexual misconduct, which he continued to deny. With his exit, experts speculated that two figures could emerge as the leading Democratic candidates: Tom Steyer, a billionaire philanthropist who previously unsuccessfully ran for president in the 2020 election, and Katie Porter, a former California congresswoman.

But another Democrat—Xavier Becerra, former Health and Human Services Secretary—has since surged in the polls. 

Two Republicans are still in the race as well, a fact that has fueled lingering concerns among Democrats that the party could end up being shut out of the general election if Californians split the vote between the more numerous Democratic candidates.

As the June 2 primary approaches, “there’s still a lot of volatility in the polls,” says Meredith Conroy, a professor of political science at California State University, San Bernardino, telling TIME that there’s no clear frontrunner in the race at this point.

Here’s what to know about where things stand.

Becerra’s rise—and the other candidates at the top of the pack

A survey released by Emerson College Polling/Inside California Politics on Wednesday found that 19% of respondents supported Becerra—a nine-point increase from the previous poll released by Emerson College last month. In March, Becerra was polling at just 3%, according to another Emerson survey. 

The latest poll found that Becerra was closely followed by Steyer and Republican candidate Steve Hilton, each of whom was backed by 17% of respondents. But that 2-point difference is within the poll’s margin of error, political scientists note, so it doesn’t mean that Becerra has a clear lead over Steyer and Hilton.

“From a statistical standpoint, we don’t have enough confidence to know which person is ahead, but we’re very confident that Hilton, Becerra, Steyer are separate from the rest of the pack based on the margin of error,” says Christian Grose, a professor of political science at the University of Southern California. “I would say that Becerra, Steyer, and Hilton are statistically tied, based on that poll.”

Conroy says that results may vary poll to poll, noting that some surveys show Steyer polling slightly ahead of Becerra. But she says that recent polls do indicate that Becerra has gained ground in the race, and that he and Steyer are the most popular Democrats in the field at this point, while Hilton, who has been endorsed by President Donald Trump and previously served as a political strategist for former British Prime MInister David Cameron, is the leading Republican candidate.

Experts propose a few possible reasons as to why Becerra has surged in the polls over the past month. Grose says some of that growth could be because of Becerra’s name recognition, since he previously served as California’s Attorney General, and that, after Swalwell dropped out of the race, some voters may have given Becerra “a second look.” Some Sacramento lobbyists who previously backed Swalwell shifted their support to Becerra after Swalwell’s exit, which may have helped Becerra’s campaign as well, Grose says.

Eric Schickler, a professor of political science at the University of California, Berkeley, says that part of the reason why Becerra has risen in the polls could be “just really good timing”: Becerra spent a lot of funds on an ad blitz that happened to come out right before the Swalwell scandal, which seems to have drawn a lot of attention to his campaign.

“The challenge was people weren’t paying attention to him,” Schickler says. “It’s almost like, once the race reopened, he had this opportunity to kind of introduce himself.” Schickler adds that Becerra is a “mainstream Democrat” who “doesn’t alienate any particular constituency,” which may also be appealing to some voters.

“There’s always been just this large mass of Democratic and Democratic-leaning voters who have not felt like any one particular candidate stuck out, but they also wanted to make sure to elect a Democratic governor, and so there’s been this bulk of undecided and movable voters,” Schickler says. “Becerra ended up being well-positioned to pick up a good chunk of those voters. But again, so far, he hasn’t consolidated enough support that you could say he’s a clear favorite.”

Grose says it’s not clear if the surge in support for Becerra will continue, noting that the candidate has also been the subject of intense scrutiny over the past month. Some former Biden Administration officials, for instance, have criticized Becerra over his tenure as Health Secretary, with one saying that “he was not effective in government.”

And many voters are still unsure of who they’ll vote for; the Emerson poll found that 12% of respondents were still undecided. It’s not unusual for that many voters to not know who they’re going to vote for leading up to a primary race, according to Conroy, and Grose says it makes sense given the number of candidates in the race.

Could the Republican candidates shut out the Democrats?

Some Democrats have been concerned that the large number of candidates in their party who are running for governor could split the vote among Democratic voters. They have worried that could potentially lead to a scenario where the two Republicans—Hilton and Chad Bianco—would be the only candidates on the ballot in November because of the state’s top-two primary system.

But experts say they think it’s unlikely that California, a Democratic stronghold, will have two Republicans on the ballot in November.

“I understand why people are concerned given how crowded the field has stayed and how competitive the field has stayed,” Conroy says. “But I think it’s unlikely. I think that 12% of undecided will largely funnel into one of the leading Democrats, and I think as we get closer to the primary, some of those Bianco voters will funnel themselves into Hilton because of the endorsement by Trump … and that will reduce the likelihood that Bianco would be in the top two.”

Support for Bianco has fallen over the past month; in April, the Emerson poll found that he had the backing of 14% of respondents, whereas the most recent poll found that he only had the backing of 11%.

Still, some Democrats have indicated that they plan to wait for more polls to come out before casting their ballots, and then vote for the candidate in their party who is polling the best just before June 2. Some experts told CalMatters they worried this strategy could inundate elections officials with ballots on Election Day, potentially resulting in a slow vote count.

But Conroy says that strategy could help the Democratic party; if voters are waiting to mail their ballots to see who has the most support in the polls, that could mean that fewer ballots would go toward candidates who would “water down” the vote, she says.

Grose says that campaigns and political consultants often urge voters to turn their ballots in as soon as possible, but if someone is "genuinely undecided” on who to vote for, “waiting a little bit is not so bad.” He advises people who are holding off on mailing their ballots, though, to be aware that there have been mail delays recently, so some ballots might not be received in time. But he adds that voters can drop off their ballots at voting centers or vote in person to avoid that issue.

Schickler says the strategy underscores the fear among Democrats that Hilton and Bianco could advance to the general election, though he thinks it’s likely that there will be at least one Democratic candidate on the ballot in November.

“It’s not a great situation when voters are basically in a position where they’re waiting for the last minute to see how the polls look,” Schickler says. “On the other hand, it’s understandable in this situation.”