I actually don't think polls are overestimating Trump by much, more that they're underestimating Haley. And I think it really comes down to undecided voters. Trump is a known quantity for pretty much everyone in America. So anyone who isn't sure if they're going to vote for him isn't unaware of his issues, but probably has some doubts about him. So my theory is that undecided voters skew, if not anti-Trump, at least Trump-skeptical and are disproportionately choosing Haley. You can see an inkling of that in the preliminary exit poll data: In Virginia, for example, voters that decided their vote choice earlier than this year went overwhelmingly for Trump (78 to 21 percent), but voters that made their decision later chose Haley (54 to 42 percent).

—Mary Radcliffe, 538

Polling nowadays is incredibly hard. Seeing response rates of under 2 percent is all too common. So even very slight differences in how fired up people are to take polls can translate into meaningful differences between polls and results. Primary polling is especially hard because you can't use partisan identification to benchmark how reasonable the sample looks. That all said, in New Hampshire and in South Carolina, I wonder if Haley may have benefited from the lack of a competitive Democratic primary, and the fact that some who might have otherwise voted in a Democratic primary were able to vote for Haley.

—Dan Hopkins, 538 contributor

What's everyone's favorite theory about why polls have seemed to consistently overestimate Trump support? (I know this was discussed some on the podcast.)

—Julia Azari, 538 contributor

Tonight I'll also be watching my home state of Arkansas, where polls just closed. There hasn't been recent polling on the GOP presidential primary there, but Trump remains popular in the conservative state, which he won 62 percent of the state in the 2020 general election. His former press secretary is the governor, Gov. Sarah Huckabee Sanders, and she endorsed him in the fall.

There's not much suspense downballot either. Rep. Steve Womack, who represents the northwest corner of the state—home to the University of Arkansas, Walmart, and other big businesses and booming towns—is fending off an unlikely challenger from his right and is the only Republican incumbent to face a challenger. That challenger, State Sen. Clint Penzo is against vaccines, the war in Ukraine, government spending and has criticized Womack's votes during the House speaker fight last fall. But Womack has represented the district for 13 years and all the advantages of incumbency.

On the Democratic side, all four candidates for the House are running uncontested.

Perhaps of a bit more interest — earlier, I wrote about the state Supreme Court races and how the outcomes there could result in a game of musical chairs leading the very conservative Sanders to make one or two appointments to the court.

—Monica Potts, 538

As we wait for the final winners of Super Tuesday's primaries to be projected, here's where things stand in the races we're tracking:

- California's 16th District: With 57 percent of the expected vote reporting, Democrat Sam Liccardo has 22 percent, Democrat Joe Simitian has 18 percent, Democrat Evan Low has 16 percent and Republican Peter Ohtaki has 13 percent. This is a solid blue district, so we expect two Democrats to advance to the general election.

- California's 20th District: ABC News has projected that Republican Vince Fong (currently at 39 percent with 52 percent of the expected vote counted) will take one of the general-election slots, but the other is still up for grabs between Republican Mike Boudreaux (25 percent) and Democrat Marisa Wood (22 percent).

- California's 22nd District: With 50 percent of the expected vote counted, Republican incumbent David Valadao has 34 percent, Democrat Rudy Salas has 28 percent, Republican Chris Mathys has 22 percent and Democrat Melissa Hurtado has 15 percent. Democrats were afraid of getting shut out of the general election in this swing seat, but that doesn't look likely to happen now.

- California's 31st District: Democrats should maybe be more worried about a lockout in this open, safely Democratic seat. With 70 percent of the expected vote in, Democrat Gil Cisneros has 21 percent, Republican Daniel Martinez has 21 percent and Republican Pedro Casas has 19 percent.

- California's 45th District: ABC News has projected that Republican Rep. Michelle Steel will advance to the general; she has 57 percent of the expected vote with 82 percent reporting. Her November opponent will either be Democrat Derek Tran (16 percent) or Democrat Kim Nguyen-Penaloza (14 percent).

- North Carolina's 8th District: With 97 percent of the expected vote in, Republican Mark Harris is at 30.4 percent, just barely above the threshold to avoid a runoff. The Associated Press has already declared him the winner.

- Texas's 32nd District: Similarly, with 99 percent of the expected vote in, Democrat Julie Johnson is at 50.4 percent, which would just barely be enough to avoid a runoff. If she does face one, it would be against fellow Democrat Brian Williams, who is at 19 percent of the vote.

—Nathaniel Rakich, 538