Nathaniel just mentioned Nikki Haley's strength in the well-educated, affluent communities around Boston. If you want to learn more about that group, its connection to the defense industry, its ambivalent views on racial integration, and its long-term movement into the Democratic coalition, check out historian Lily Geismer's book "Don't Blame Us".

—Dan Hopkins, 538 contributor

Trump is speaking now (right on schedule, for once!) and it's one of those "pivot to the general" speeches candidates give once they win the nomination. But it's also like he's playing his greatest hits on 1.5x speed: In the last five minutes, he has talked about immigration (saying migrants are coming in on airplanes), ISIS (he says he wiped them out in four weeks), inflation (chastising "Bidenomics") and energy generation, and he attacked Biden for his age (at one point claiming that the president cannot lift a beach chair which "weighs nine ounces").

One thing missing? Any mention of Haley. Remember, Trump is not technically the nominee until the convention says so, and he's not the presumptive nominee until he wins enough delegates. He is having a super Super Tuesday tonight, but he's not quite there ... yet.

—G. Elliott Morris, 538

Dean Phillips's tepid campaign may not last until the morning. Phillips has previously stated that he would drop out and endorse the likely Democratic nominee if his campaign wasn't viable after Super Tuesday. So far, his highest level of support tonight is in Oklahoma, where he's currently pulling 9 percent of the Democratic primary vote. That's closely followed by his home state of Minnesota, where he's winning a similar level of support. But at least he can say he won something today: tiny Cimarron County in the Oklahoma panhandle, where he currently leads Biden by five votes out of 21 total that were cast.

—Cooper Burton, 538

Trump is winning Massachusetts 61 percent to 36 percent, but as you can see in the map below, Haley is winning Boston and many of its well-to-do western suburbs like Concord, Wellesley and Weston. While these towns are now solidly Democratic, they are also home to a lot of the fiscally conservative, socially liberal voters who have supported moderate Republicans for governor like Mitt Romney and Charlie Baker. It’s basically the exact kind of well-educated voter that hates Trump but misses the old Republican Party, which Haley has become an avatar for.

—Nathaniel Rakich, 538

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