Turning back to the high-stakes GOP primary in Alabama's 1st District, Moore leads Carl 55 percent to 45 percent, with 87 percent of the expected vote reporting. This undoubtedly makes Moore a favorite to win, but it's not over just yet. That's because 90 percent of the expected remaining votes are in Mobile County, Carl's home base. So far, Carl has carried Mobile 72 percent to 28 percent. That's been extremely helpful to him, but he'll need to win the remaining votes by an even larger margin if he wants to catch Moore: Based on the remaining votes, that same vote share would only get Carl to 48 percent (to Moore's 52 percent).

—Geoffrey Skelley, 538

For those just joining us, here’s the scorecard in the presidential race tonight. Trump has won 12 contests thus far, while Haley has won only one (Vermont). We are still waiting for a winner to be projected in Utah and Alaska.

—Nathaniel Rakich, 538

Now that the California Senate race has been projected, and more or less matches what we expected from pre-election polling, Schiff and Garvey will move on to the general election. Voters priorities in the state reflect its Democratic bent, giving us more hints that Schiff is well-positioned for a big lead in the general.

In polling before the primary, voters said abortion was the most important factor for their senate vote. In a late February University of California Berkeley/Los Angeles Times survey, 55 percent of likely California primary voters say that being "a strong voice in defending abortion rights" is very important to their Senate vote, more than any other candidate quality tested. For voters that say they plan to vote for Schiff, Porter or Lee (the top three Democrats in the race), 84 percent say defending abortion is very important, compared to just 15 percent among those who say they plan to vote for Garvey, the leading Republican.

Other top candidate qualities in the survey include being "a strong opponent of Donald Trump" (51 percent say this is very important) and supporting tougher immigration laws (46 percent). Among the top four candidates, Lee supporters were the only group among which a majority (63 percent) said supporting an immediate cease-fire in Gaza is very important, compared to 42 percent of Porter supporters, 33 percent of Schiff supporters and 13 percent of Garvey supporters.

—Mary Radcliffe, 538

In a few races, the Democratic Congressional Campaign Committee has endorsed a candidate ahead of the primary — a relatively rare step for the group. Most of those candidates are doing pretty well tonight. In Texas, Michelle Vallejo easily clinched the nomination for the 15th District, which is the only really competitive House seat in the state. In California, most of the DCCC's candidates don't actually have primary challengers, but one, Rudy Salas, is in a tough fight for a spot in the general election. Democrats are anxiously hoping to avoid a lockout in the 22nd District, where Salas is looking for a rematch against Republican David Valadao.

—Jacob Rubashkin, Inside Elections

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