I just want to underscore Elliott's point about how hard polling has gotten with a quick story I wrote up in a paper with Tori Gorton called "On the Internet, No One Knows You're An Activist." We were trying to survey lower-engagement voters, so we drew a sample of 9,937 registered Pennsylvania voters who hadn't consistently voted 2012-2018. Then, we matched them to Facebook accounts and served ads to 1,321 inviting them to take a survey. 66 people clicked on our ad, 7 began the survey, 6 completed it, and 1 person left an email for follow-up. I of course want to express my deep gratitude to that one respondent. But beyond that, a 0.4% response rate magnifies sampling errors, because very small differences in people's willingness to take polls can add up to very large errors in vote margins. That's especially true in primaries, where pollsters can't use partisan identification to stabilize the results.

—Dan Hopkins, 538 contributor

We've been tracking Trump's non-incumbent endorsees (because endorsing the incumbent is kind of a gimme) tonight, and so far he's 4 for 4 of the races called. Addison McDowell, Trump's pick in North Carolina's GOP primary for the 6th District, is also leading. But in California, state Assemblyman Vince Fong, who received Trump's endorsement for the Republican primary in the state's 20th District (Kevin McCarthy's old seat), is trailing at 26 percent with 23 percent of the expected vote reporting.

—Kaleigh Rogers, 538

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

In California's 40th District, with 46 percent of the expected vote in according to the Associated Press, engineer Allyson Damikolas (endorsed by EMILY's List), is trailing former fire captain Joe Kerr (endorsed by the Congressional Progressive Caucus PAC). The 40th is a key target for Democrats, who are looking to win back some of the ground they gained (and then lost) in the Orange County area. The 40th District spans Riverside and San Bernardino Counties, too.

—Meredith Conroy, 538 contributor

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