In several of California's open congressional districts, tonight could be the end of any suspense about who the next representative will be. Or, it could be the start of an eight-month intraparty slog.

That's because California's unique all-party primary system — where the top two primary vote-getters advance to the general election — allows for either a traditional contest between a Democrat and a Republican or a fight between members of the same party in the general election, and it's not always obvious which one you're going to get. That's the case in at least four open-seat races today — three Democratic and one Republican.

In California's 16th District, there are nine Democrats but just two Republicans vying to replace Democratic Rep. Anna Eshoo. While limited polling of the district suggests that former San Jose Mayor Sam Liccardo or Santa Clara Supervisor Joe Simitian, both Democrats, are the front-runners, if one of the two Republicans consolidates most of the GOP vote and the Democratic vote scatters among the many candidates, a Republican could finish in the top two. In the 2022 primary, the Republican candidates didn't meet that threshold, splitting a combined 22 percent of the vote; the four GOP candidates in the state's Senate race won a combined 24 percent in the district. A Republican advancing would ensure that whichever Democrat also finished ahead would win the general election in November, given the district's partisan bent. But if two Democrats finish in the top two, it'll be a real race.

Same goes in the 30th District, where Adam Schiff is leaving to run for Senate. Twelve Democrats and just two Republicans will appear on the ballot there. In the 2022 primary, four GOP House candidates totaled 21 percent, and Senate GOP candidates combined for a smaller 22 percent. Democratic state legislators Anthony Portantino and Laura Friedman, and Democratic former city attorney Mike Feuer are the front-runners for this seat; if two of those three make it to the general election, it will be an expensive and sharp-elbowed race to November, but if one of the Republicans squeezes in, it's basically over.

In the 31st District, where Democrat Grace Napolitano is retiring, six Democrats and two Republicans are running. In 2022, the one Republican running for the seat, Daniel Martinez, advanced to the general by winning 37 percent of the vote in the primary. Former Rep. Gil Cisneros, state Sens. Susan Rubio and Bob Archuleta, former Monrovia Mayor Mary Ann Lutz and attorney Greg Hafif are all running well-funded Democratic campaigns, creating the possibility that Martinez, who is running again, could finish in the top two instead of two Democrats, effectively ending this race tonight.

And in Kevin McCarthy's old seat, the 20th District, it's a similar story with the parties reversed. There, the two Democrats will probably combine for around 30 percent of the primary vote (in 2022, the House candidates combined for 30 percent and the Senate candidates for 32 percent), while six Republicans fight over the remaining 70 percent (a seventh dropped out but remains on the ballot).

—Jacob Rubashkin, Inside Elections

Although the race has mostly gone as expected, with Trump securing most of the delgates in the first several GOP nominating contests, Republicans still say they are paying attention, according to a February Echelon Insights survey. Seventy-nine percent of Republican likely voters in the survey say they are paying a lot of or some attention to the race, while just 20 percent say they’re paying only a little or no attention at all. Among those who aren’t tuning in, 36 percent say the number one reason is because they’re tired of politics, while 17 percent say it’s too early and 15 percent say they don’t think the race is competitive.

—Mary Radcliffe, 538

On Sunday, Republicans in Washington, D.C., voted for Haley by nearly 30 percentage points in the GOP's party-run primary, giving her all 19 national delegates from the nation's capital. This marked her first victory anywhere in this year’s primary contest, and the first ever primary or caucus victory for a woman in the history of Republican nomination races. Yet the other contests that took place just ahead of Super Tuesday otherwise showcased Trump's strong hold over his party's base. This included victories on Saturday in caucus-convention races in Idaho, Michigan and Missouri, and in North Dakota's Republican caucuses on Monday.

In Michigan, Republicans gathered at Saturday's state party convention to allocate 39 national delegates from the state’s 13 congressional districts (three per district). The voters consisted of precinct delegates mostly elected at the August 2022 state primary as well as Republican elected officials, and they handed Trump all 39 district-level delegates. This result brought Trump's Michigan haul to 51 of the state's 55 delegates, after he had already won 12 of its 16 at-large delegates in the Feb. 27 primary.

The Michigan GOP's split primary-caucus approach came about in part because national Democrats added Michigan to the early part of their presidential primary calendar, prompting the Democratic-controlled state government to shift the state’s primary date into late February. Since the new date violated the national GOP's calendar rules, Michigan Republicans used a workaround whereby the primary results would allocate the state's at-large national delegates, but the state party didn’t formally make the allocation until March, at Saturday’s caucus-convention that also allocated district-level delegates.

Trump also swept caucuses in Idaho and Missouri on Saturday, and then North Dakota on Monday. In Idaho, Trump won 85 percent of caucusgoers, easily surpassing the state's 50 percent winner-take-all threshold to capture all 32 of Idaho's national delegates. In Missouri, Trump won every state- and congressional district convention delegate elected at local caucuses around the state, all but guaranteeing that he will sweep all 51 national delegates when the district and state conventions formally allocate delegates in April and May, respectively. And in a near-repeat of Idaho, Trump won 84 percent of caucusgoers in North Dakota on Monday to claim all 29 of the state’s national delegates.

—Geoffrey Skelley, 538

Based on each state's politics and demographics, 538's G. Elliott Morris has calculated how many delegates both Trump and Haley need to win in each state today to be on pace for the nomination. Here are those numbers:

In total, Trump's magic number tonight is 497 delegates, while Haley's is 543. Elliott's model thinks Trump needs to sweep Arkansas, California, Tennessee and Texas while also taking about half of the delegates available in Alaska, Colorado and North Carolina. Meanwhile, if she wants to have a shot at winning the nomination, Haley must win all the delegates in Alabama, California, Maine, Massachusetts, Minnesota, Oklahoma, Utah, Vermont and Virginia — a tall order on a night where winning even one state isn't a certainty.

—Nathaniel Rakich, 538