Haley is now speaking live from Charleston, South Carolina, and she just announced she is suspending her campaign. There are now no major Republican candidates left running against Trump.

—Nathaniel Rakich, 538

While you were sleeping, ABC News projected Trump as the winner in the last two presidential contests: Alaska and Utah. Trump currently leads in Alaska 88 percent to 12 percent and in Utah 57 percent to 42 percent.

—Nathaniel Rakich, 538

After a full-ish night's sleep, we're back on the live blog as the winners of several House primaries from Super Tuesday remain unknown. However, the big news this morning is that campaign sources are telling ABC News that Haley will suspend her campaign for president after winning just one primary yesterday, making Trump the presumptive Republican nominee. She will deliver remarks at 10 a.m. Eastern, and we'll cover it live right here.

—Nathaniel Rakich, 538

It's just past 2 a.m., and we've got major results in from most of Super Tuesday's wide-ranging slate of primary contests. So far, Trump has won at least 12 of the 15 states holding GOP presidential nominating contests, while Haley has won Vermont — though whether she hits a 50 percent (plus one vote) threshold of victory there will determine the exact number of delegates she takes home.

Either way, with an estimated 943 total delegates to Haley's 86 so far, per ABC News projections, Trump's well on his way to securing the magic delegate majority number of 1,215 — though it will take at least another week. He's so far secured 667 delegates tonight and is likely to hit the 769 mark that Elliott noted earlier would set him up to mathematically clinch the nomination on March 12. Of course, we're all watching to see if Haley drops out sooner.

In other highlights:

- As expected, Republican Lt. Gov. Mark Robinson and Democratic state Attorney General Josh Stein secured their parties' respective nominations, and will go head to head in what's expected to be a close general election contest for governor.

- Rep. Colin Allred locked up the Democratic nomination in Texas's Senate race, and will face off against Sen. Ted Cruz in the general.

- Democratic Rep. Adam Schiff secured not only the top spot in a top-two primary, but also a likely glide path to the nomination, as the second spot on November's ballot went to Republican Steve Garvey instead of a second Democrat.

We're still tracking a dozen-odd downballot races that have yet to be projected, and awaiting presidential primary results in Utah and Alaska, so we'll see you back here tomorrow ... er, later today, with more results and analysis!

—Tia Yang, 538

Four years ago, Super Tuesday was one of the last big news events before the declaration of the COVID-19 pandemic. Just days later, the U.S. and much of the world would go into lockdown in an effort to stem the virus's spread.

As Julia noted, in 2020, Super Tuesday marked the point when the Democratic Party consolidated behind Biden. But I think that, partly because of the pandemic, even close observers of American politics don't appreciate just how unlikely Biden's Super Tuesday comeback was.

This year in Iowa, Ron DeSantis's second-place finish with 21 percent of the vote was enough to effectively end his campaign. But in 2020, Joe Biden came in fourth in the Iowa Democratic caucuses.

Similarly, pundits have viewed Trump as the prohibitive favorite in the 2024 race since at least his New Hampshire victory, when he topped Haley 54 percent to 43 percent. In 2020, however, Biden's New Hampshire performance was far weaker than Haley's this year — he finished fifth in the state, winning just 8 percent of Democratic primary voters.

But in a very short period four years ago, Biden resurrected his campaign. He convincingly won South Carolina on Feb. 29 thanks to his strength with Black voters, who had been few and far between in Iowa and New Hampshire.

Then, both Amy Klobuchar and Pete Buttigieg endorsed Biden in the run-up to Super Tuesday, consolidating the more moderate side of the Democratic Party against Bernie Sanders. That, in turn, positioned Biden for a decisive Super Tuesday win that made him the front-runner in short order. While Sanders won California, Biden won 10 states, including Massachusetts, North Carolina and Texas.

What explains the dramatic change in Biden's fortunes over a few short days leading up to Super Tuesday in 2020? In his book "Learning from Loss," political scientist Seth Masket emphasizes the Democrats' overwhelming aim to defeat Trump, and to find a candidate who gave them the best chance of doing so. At the time, there was evidence that Biden ran better against Trump than other Democrats. Many Democrats were willing to follow the cues of party leaders about their most competitive candidate, and in doing so, they vaulted Biden to the nomination.

In this year's GOP primary, there's some evidence that Haley may be a stronger general election nominee than Trump. But in a late-November survey I conducted via YouGov, GOP voters overwhelmingly saw Trump, not Haley, as their strongest candidate, and there's no evidence that's changed. So on the Republican side, the grounds for a similarly sudden Super Tuesday switch just aren't there.

—Dan Hopkins, 538 contributor