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

The biggest downballot race in California is its U.S. Senate contest. Although 27 candidates filed for the race to fill the seat of the late Democratic Sen. Dianne Feinstein — who died last fall — the four leading contenders are Democratic Reps. Adam Schiff, Katie Porter and Barbara Lee, plus Republican Steve Garvey, a former Major League Baseball player. The front-runner appears to be Schiff, who is polling at around 25 percent in 538's California primary polling average. This puts him just a bit ahead of Garvey and Porter, who are right around 20 percent for the coveted second spot. Behind them is Lee, who is polling just under 10 percent.

The race has largely centered on Schiff and Porter, both of whom are fundraising powerhouses. As of Feb. 14, Schiff had brought in $29.8 million in net contributions, while Porter had collected $16.7 million, putting them each well ahead of Lee ($4.8 million) and Garvey ($2.1 million). The two leading Democrats also brought over huge sums left over from their House accounts — $21 million for Schiff and $7.4 million for Porter.

In the final weeks, Schiff has tried to use his massive campaign war chest to push Garvey into second place. Schiff has run ads that attack Garvey for his conservative views and past support for Trump, but the spots intend to raise Garvey's profile among Republican voters. By doing that, Schiff could help Garvey consolidate the GOP vote and finish ahead of Porter, relieving Schiff of a demanding general election campaign against the fellow Democrat. A pro-cryptocurrency super PAC may also help Schiff out, after swooping in with $10 million in outside spending seeking to derail Porter.

—Geoffrey Skelley, 538