Super Tuesday primaries 2024: Trump and Biden dominate, Haley drops out

538 tracked how Trump and Haley did, plus key U.S. House and Senate races.

March 5 was Super Tuesday — the biggest election day of the year until the one in November! With former President Donald Trump projected to win 14 of the day's 15 GOP presidential nominating contests, former U.N. Ambassador Nikki Haley announced Wednesday morning that she is suspending her campaign.

It was also the first downballot primary day of 2024, with important contests for Senate, House and governor in states like Alabama, California, North Carolina and Texas.

538 reporters, analysts and contributors broke down the election results as they came in with live updates, analysis and commentary. Read our full live blog below.


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Republican primary voters want Haley to drop out

Given that Haley almost certainly wins Vermont (though whether she clears 50% and takes all the delegates is yet to be seen), she may be less likely to drop out of the race. But most Republican primary voters would rather see her move on: according to a February poll by Emerson College Polling, 56 percent of likely Republican primary voters nationwide say that Haley should drop out of the race for the Republican nomination. Thirty-one percent say she should stay in, and 13 percent are not sure.

—Mary Radcliffe, 538


Arkansas State Supreme Court results

In Arkansas, Justice Courtney Hudson won a race for position 2 on the state Supreme Court. She currently holds position 3, but ran for the vacant position 2 because of complicated judicial retirement rules. Her win will leave her current seat vacant, which will give Sanders the opportunity to appoint a replacement for the rest of the term. There is also a 4-way race for the chief justice spot, but if no candidate wins a majority tonight, the top two will head on to a runoff in November.

—Monica Potts, 538


Tight race in North Carolina’s 10th District

With nearly all expected votes counted in the Republican primary for North Carolina’s 10th District, it’s a tight race between moderate Pat Harrigan, who has 41 percent of the vote, and conservative Grey Mills, who has 39 percent. Whoever wins will be heavily favored to win the general election in this dark-red seat, which is open because Rep. Patrick McHenry is retiring.

—Nathaniel Rakich, 538


Will the VIEWPAC-endorsed candidate win in Alabama's 2nd District?

In the Republican primary, attorney Caroleene Dobson is trailing businessman Dick Brewbaker in Alabama’s 2nd district, with 40 percent of the expected vote reporting. This race is an open primary due to redistricting, where eight Republicans are running for the nomination. Dobson had received an endorsement from VIEWPAC, an organization that formed in 1997 to elect more Republican women to office.

Meredith Conroy, 538 contributor


More thoughts on primary polls

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