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

If the polls are right, there will be very little drama tonight in presidential races: Trump has massive leads over Haley in virtually every state. For instance, here's what our primary polling averages say in the six states with enough polling to calculate one:

Trump also leads by at least 42 percentage points in the few state-level polls we have this year from Alabama, Maine, Minnesota and Oklahoma. His lead is smaller, though still substantial, in the most recent surveys of Utah (27 points) and Vermont (30 points). Unfortunately, we're flying blind in the last three states; we don't have any polls of Arkansas since last fall, or any polls of Alaska or Colorado, period.

But what if … the polls are wrong? Even in the states where we've calculated averages, there is precious little truly recent polling. The only polls of Super Tuesday states conducted entirely within the last month were four of California, two of Maine, one of Minnesota, two of North Carolina, one of Texas, one of Vermont and one of Virginia. That's not a lot of data to go off.

Plus, primary polls so far this year have overestimated Trump's margin over Haley. This isn't necessarily unusual; since 2000, presidential primary polls have had an average error of 9 points. But the fact that the direction of that error has been consistent so far is … interesting. We usually caution against trying to predict the direction of polling error in advance, but this could — could — indicate that pollsters' likely-voter models for the primary are too weighted toward the Trump wing of the GOP.

As Geoffrey and I wrote yesterday, there are certain states — Colorado, Massachusetts, Vermont and Virginia — that seem demographically favorable for Haley. Despite what the polls say, I wouldn't be totally shocked if Haley pulled off a win in one of them. As noted, Colorado hasn't seen any polling this cycle, and Massachusetts hasn't seen any in a month. And while a poll gave Trump a 30-point lead in Vermont a few weeks back, the most recent poll of Virginia put Trump's lead over Haley at just 8 points among likely voters.

—Nathaniel Rakich, 538