Based on an analysis of the vote, ABC News projects that Trump and Biden will win their presidential primaries in Arkansas. With about 7 percent of the expected vote in, Womack is holding onto his lead in the 3rd Congressional District 60 percent to 40 percent against Penzo.

—Monica Potts, 538

I'll be very interested to see, when the dust settles tonight, if the polls are more on the money in states with closed primaries, where bored (or wily) Democrats can't vote in the Republican Party primary for Haley. A lot of the exit polling data we've seen on Haley supporters and who they'll vote for in the general election, or whether they approve of Biden's job performance, makes me wonder how many of her voters are just plain old Democrats who are getting screened out of a lot of GOP primary polling. But we'd see a difference in closed primary states (to the extent we have robust polling there to make the comparison)!

—Jacob Rubashkin, Inside Elections

Julia, I'm suspicious that the reason Trump's lead in primary polling has been somewhat exaggerated is that pollsters are not necessarily capturing some of the independents who are showing up to vote in a GOP primary. As Nate Cohn recently pointed out in The New York Times, some pollsters have filtered for likely GOP primary voters by mostly or only looking at voters who've voted in Republican primaries. But a fair number of independents, including Democratic-leaning ones, wouldn't necessarily fall in that category. But with Biden a lock to win the Democratic nomination — barring something happening outside of the voting booth — Democratic-leaning voters have only one race to get involved in. Although we know there aren't that many "cross-over" voters who participate in the opposing party's primary, some high-propensity Democratic voters and some Democratic-leaning independents have probably voted in states that allow non-Republicans to cast ballots in the GOP primary.

—Geoffrey Skelley, 538

In 2016, people who said they were undecided in polls were more likely to vote for Trump as "professor polls" explains in this great 538 video I show my students. But in 2024, Trump supporters aren't so shy. It's the rest of the GOP that might be more bashful.

—Meredith Conroy, 538 contributor

It has become somewhat of a theme of our live blogs this primary calendar to note that Trump's challengers are beating their polls. This first looked to be the case in New Hampshire, where polls significantly underestimate support among Republican likely voters for Haley. But the pattern is more robust than one state: In fact Haley has been beating her polls by an average of five points (in vote share) once you account for undecided voters in these surveys. The consistency of this pattern is striking enough to warrant a post on the matter.

As Mary said earlier, polling primaries is hard! That is betrayed by the fact that POTUS primary polls are by far the least accurate type of poll in 538's pollster rating database going back to 1999. But error is different than bias, and when most of the polls are off in the same direction, something has gone awry.

That "something" is likely the difficulty in obtaining opinions of moderate Republicans from samples of "likely Republican primary voters." Remember that fewer than one percent of people called for a poll actually complete the interview. That means the ones that do are statistical "weirdos" (excuse the technical language). Pollsters adjust for this by weighting their samples to known population benchmarks — like the percent of all adults who are white, over 65, have a college education etc. But in primaries, such benchmarks do not actually exist; pollsters are just making educated guesses about them.

My theory is that most of these primary polls pulling samples of voters from voter registration lists are missing moderate crossover partisans and first-time voters. Additionally, we know that people who are highly motivated to participate in polls (the "weirdos") also happen to be the most politically and ideologically extreme Americans. That's a recipe for polling bias in primaries, where weighting to party, past vote and polarized demographic benchmarks does not control for the partisan consequences of overrepresenting politically engaged Americans.

Now, none of this is to say that polling is "broken." It's just hard to precisely sample a population that doesn't really exist. The polls for the 2024 primary still have below-average error, historically speaking, so we shouldn't go throwing out the baby with the bathwater. But this could nevertheless be a sign of pollsters having a hard time reaching moderate "normie" voters. And if that persists, it could have consequences for general election polls too.

—G. Elliott Morris, 538