I've already gone on about Phillips a bit tonight, but I think it's interesting that he tried to challenge Biden from the center, or mostly on the basis of personal characteristics. This feels notable because Biden's major weakness would seem to be from the left. But the main vehicle for opposition votes to Biden has been the "uncommitted" movement — not a specific candidate. This might be because the progressive wing of the party doesn't have a younger and agreed-upon candidate yet, or because they see Biden as the best realistic bet for achieving some of their policy goals.

—Julia Azari, 538 contributor

As Monica just noted, about the only drama in the presidential primary contests tonight can be found in Vermont, where Haley actually might defeat Trump in a traditional, state-run primary (unlike the party-run primary she won in Washington, D.C., over the weekend).

So, what's going on in Vermont? Fundamentally, the Republican primary electorate just isn't as conservative in Vermont. I've been using the 2016 Republican nomination race as a back-of-the-napkin guide to the makeup of the GOP electorate this year, and it's been useful. At this point, we could split the GOP into two parts: those who voted for Trump, Ted Cruz and Ben Carson, who tend to make up the Trumpier part of the GOP now; and those who backed Marco Rubio and John Kasich, who aren't as inclined to back Trump. Looking at how the Super Tuesday states voted in 2016, you'll notice that Vermont is the only state voting today in which the combined vote share for Rubio and Kasich outdistanced the Trump, Cruz and Carson cohort.

Back in 2016, the types of voters who backed Rubio and Kasich tended to be more moderate and more likely to hold a four-year college degree. In that sense, they attracted parts of the GOP coalition (and beyond) that make up much of Haley's coalition this year. As we already discussed, some Democratic-leaning voters may have helped Haley in every contest, and Vermont happens to also be a very blue state full of those voters.

—Geoffrey Skelley, 538

With Texas Republican Sen. Ted Cruz projected to win his primary — he's got 89 percent of the votes counted so far — the question becomes whether he will face as tough a race in November as he did back in 2018. Six years ago, he beat Beto O'Rourke by just 2.6 percentage points, raising questions about whether Democrats could actually win a statewide federal race in the Lone Star State. But recently, his approval rating has notched up after being underwater for much of 2021 and 2022. On the Democratic side, Colin Allred is winning 62 percent of the Democratic vote with just over half the expected vote in.

—Dan Hopkins, 538 Contributor

In the Democratic primary for the Texas’s 15th Congressional District, Michelle Vallejo is leading with 32 percent of the expected vote in. She ran unsuccessfully for the seat in the 2022 midterms, but she’s leading her opponent, John Villarreal Rigney, 73 percent to 27 percent, according to The New York Times. Villarreal Rigney tried to run as the more conservative candidate, but Vallejo has the endorsement of much of the Democratic establishment and the pro-Israel group, Democratic Majority for Israel, or DMFI. AIPAC has endorsed her Republican opponent, the current incumbent, Rep. Monica de la Cruz. If Democrats can flip any seat in Texas, this is a likely one, making this race potentially competitive in November. Both AIPAC and DMFI have invested on the Democratic side to try to fend of progressive, anti-war challengers in Congress.

—Monica Potts, 538

Super Tuesday has over 40 years of history that are deeply entwined with a bunch of issues in the presidential nomination process. The term "Super Tuesday" was first used in 1980 but was promoted by Democrats in 1988 as a deliberate effort to give an advantage to more moderate candidates. This was a direct reaction to the idea that the party's 1984 nominee, Walter Mondale, had lost to Ronald Reagan because he was too liberal. This strategy didn't really work out, though, and Democrats ended up nominating another northern liberal, Michael Dukakis.

In other words, this early attempt at a Super Tuesday brought some of the disadvantages of a regional primary, reducing the amount of attention on individual states and pressuring states to move their primaries earlier without really strengthening the influence of the region. Another drawback was that, by trying to enhance Southern influence by holding contests early, Super Tuesday also contributed to the "front-loading" problem", or the issue of having too many delegates selected at the beginning of the primary calendar.

Over time, Super Tuesday has taken on other significance as an important turning point in the race. As party politics scholar Caitlin Jewitt noted, in 2016, everyone thought that Sen. Ted Cruz needed to do well on Super Tuesday, which was heavily concentrated in Southern states where he needed to rack up wins — and when that didn't happen, it was a significant blow to his candidacy. For Biden in 2020, Super Tuesday marked the point when the party consolidated behind him. And in 2008, Super Tuesday made it clear that the Democratic nomination was a real race between Hillary Clinton and Barack Obama, as neither one scored a decisive victory.

It's hard to know exactly how this will play out in 2024. Republicans don't have the same ideological history with the big primary day as Democrats do. But the potential for a turning point in the race is there: Because so many delegates are at stake today, unless Haley wins a significant share of them, it may not make sense for her to stay in the race after tonight.

—Julia Azari, 538 contributor