California, a state known for having a lot of ballot initiatives, has only one statewide proposition on the ballot today: Proposition 1>), a measure that would expand funding for substance use disorder and mental health treatment and programs, including housing support. Pre-election surveys suggest the measure will pass overwhelmingly: in an average of polls conducted since January 1, 61 percent of voters support the measure, while 31 percent oppose it.

—Mary Radcliffe, 538

We're watching nine U.S. House primaries in California, five in seats that are broadly viewed as potentially competitive in November.

We'll start with the 22nd District in the Central Valley. Republican Rep. David Valadao faces a primary rematch with two of his 2022 opponents, former state Assemblymember Rudy Salas (a Democrat) and businessman Chris Mathys (a Republican). Valadao, who voted to impeach Trump after Jan. 6, only narrowly advanced to the general election ahead of Mathys before narrowly defeating Salas in November. Joining this year is Democratic state Sen. Melissa Hurtado, who could split the Democratic vote enough to give Republicans a shot at claiming both general election spots.

Four other competitive seats are partly or wholly in Orange County. First, the open 47th District is a top GOP target. Republicans have mostly rallied behind Scott Baugh, who lost this seat by only 3 points in 2022. Baugh looks likely to face one of two Democrats, state Sen. Dave Min or attorney Joanna Weiss, who are in an ugly fight for second place. Min has endorsements from Porter and the state party, but his position was weakened when he was cited for driving under the influence last May. Weiss has a slight fundraising edge, raising $2.2 million to Min's $1.7 million, and she's also received far more outside support. Next door in the 45th District, Republican Rep. Michelle Steel will likely advance with one of two Democrats. Army veteran and attorney Derek Tran has led the way in fundraising with $647,000, and has earned endorsements from VoteVets and AAPI Victory Fund, while Garden Grove City Councilmember Kim Nguyen-Penaloza has raised $315,000, and has backing from the state party, the Congressional Hispanic Caucus's BOLD PAC and labor groups.

Nearby in the 40th District, Republican Rep. Young Kim is contending with two Democrats: retired Orange County Fire Capt. Joe Kerr and Tustin school board member Allyson Muñiz Damikolas. Kerr has raised $1.1 million to Damikolis's $550,000, but Kerr has self-funded much of his haul. Kerr has Gov. Gavin Newsom's endorsement as well as backing from various labor groups, while Damikolas has support from EMILY's List, BOLD PAC and 314 Action. To the south, four mostly self-funding Republicans are vying to take on Democratic Rep. Mike Levin in the 49th District. Advertising executive Margarita Wilkinson has loaned her campaign $1.5 million of the $1.8 million she's raised, while car dealership owner Matt Gunderson has self-funded $700,000 of his $1.2 million total. The same is true of the other two candidates, Marine veteran Kate Monroe and auto-industry executive Sheryl Adams, who've raised less than $400,000 each.

The remaining races are in safe seats, where it's possible — even likely — that two candidates from the same party will advance to November. Jacob will have more on those races shortly, and you can read about them in our full California (and Alabama) race preview from last week.

—Geoffrey Skelley, 538

For the past three election cycles, 538 has tracked key progressive groups' endorsees to get a sense of Democrats' intraparty dynamics following the 2016 presidential primary, which drew out sharp ideological factions and spurred an ambitious progressive movement working to make its mark on the party. For example, in 2018, now-Reps. Alexandria Ocasio-Cortez and Ayanna Pressley shocked the political world by unseating 20-year incumbents in Democratic primaries. In 2020, fellow progressives Jamaal Bowman and Cori Bush won their own upsets against long-serving members. But in 2022, fewer progressives were successful in unseating incumbents. One was Oregon's Jamie McLeod-Skinner, who defeated Rep. Kurt Schrader despite Biden's endorsement of the incumbent, but went on to lose in November.

Today's races may not answer whether progressives candidates this year will unseat incumbents — none of the races we're watching tonight pit incumbents against notable progressives. Has the progressive caucus's appetite to challenge incumbents cooled as they worked with the rest of their party to help Biden pass his legislative agenda? Or are they preoccupied preparing to play defense against expected challengers of their own?

At least one incumbent on a primary ballot today notably doesn't have a progressive challenger: In Texas's 28th District, progressives have passed on a third attempt to unseat Rep. Henry Cuellar, after backing attorney Jessica Cisneros in both 2020 and 2022. In those cycles, progressive groups attacked Cuellar's conservative positions on issues like abortion and gun control, but Cuellar narrowly defeated Cisneros each time. Although the state director of the Working Families Party has criticized Cuellar this cycle, no progressive challenger has emerged, and today he will coast to the nomination.

Of course, progressive candidates aren't just trying to replace incumbent Democrats who they think are out of step with the modern party. They're running in primaries for open and competitive races all over the country, like California's Senate contest and California's 40th District race, where Democrats hope to unseat Republican Rep. Young Kim in November. To get the full picture of the progressive wing's electoral strategy and success rates in 2024, we're once again tracking candidates who have received endorsements from any of the following key progressive groups: Justice Democrats, Indivisible, the Working Families Party, the Congressional Progressive Caucus PAC, the Sunrise Movement, and Sen. Bernie Sanders.

Throughout the evening, we'll share tables like this one with updated results as we find out how progressives (and other candidate groupings in both parties — like women and Trump endorsees) fare in today's primaries.

—Meredith Conroy, 538 contributor

If you’re wondering what races you should be watching when — or how much coffee you’ll need to drink tonight — we’ve got you covered! Here’s a rundown of when polls will be closing across the country.

The first polls will close in Vermont and Virginia at 7 p.m. Eastern, followed by North Carolina at 7:30 p.m. — our first state of the evening with downballot races. The busiest stretch for returns will probably be after 8 p.m., when polls close in six states, including Alabama and (almost all of) Texas, which are hosting a number of competitive primaries for Congress, state legislature and more.

And if you’re in it for the long haul, you’ll want to stick around to get a first look at returns in California, the state with the most delegates up for grabs — not to mention a slew of high-profile House races and the most expensive Senate race of the cycle. Polls close in the Golden State at 11 p.m. Eastern, but as usual, we’ll only get a sneak peek tonight: The state accepts mail-in ballots until March 12 as long as they’re postmarked by today, and projections in close races could take days or even weeks.

—Tia Yang, 538