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

Yesterday, the Supreme Court rejected the legal arguments claiming that Trump could be disqualified from running for president in 2024 because of his connection to the Jan. 6 insurrection at the U.S. Capitol. Section 3 of the 14th Amendment states that anyone who held a public or constitutional office and has engaged in insurrection is ineligible to hold office in the future, unless Congress passes a law stating otherwise. Section 5 says that Congress can also pass laws to enforce any of the provisions in the amendment. Lawsuits in several states came forward to disqualify Trump on these grounds.

But until recently, very few people had given much thought to this part of the 14th amendment since the years immediately following the Civil War. Legal scholars brought up a couple of ambiguities — did it apply to the presidency, since a number of offices are named, but not the president? Do we have an agreed upon definition of what counts as participating in an insurrection and whether Trump did that in 2021? (Spoiler alert: No.)

The Supreme Court ruled unanimously that the state of Colorado could not disqualify Trump, though there were disagreements about how far to take that ruling. A majority held that Congress would need to pass a law in order to enforce Section 3. Though the unanimity of the ruling papered over some of the partisan politics, the timing was impossible to separate from political considerations, since it came just in time for today’s big round of contests.

—Julia Azari, 538 contributor