South Carolina, Nevada primaries and Ohio special election: Nancy Mace, Sam Brown win

Nevada's 3rd District is a light-blue seat around Las Vegas held by three-term Democratic Rep. Susie Lee that will likely host the state's most competitive House race. The two most notable Republican contenders may be video game music composer Marty O'Donnell and former state Treasurer Dan Schwartz, although policy analyst and advocate Drew Johnson and former state Sen. Elizabeth Helgelien are also in the mix. O'Donnell has Republican Gov. Joe Lombardo's endorsement, and he'd raised $541,000 as of May 22 ($500,000 out of his own pocket). That was less than the $922,000 Schwartz had raised ($900,000 in self-funding). But on May 24, O'Donnell gave himself an additional $700,000, meaning he's likely outdistanced Schwartz's total. Meanwhile, Johnson has raised $432,000 ($300,000 self-funded) and Helgelien has raised $282,000.

Interestingly, O'Donnell has said he won't accept money from corporate political action committees, a line we more typically hear from Democrats. This may help explain why Johnson has called O'Donnell a "Seattle liberal." Meanwhile, Schwartz has cast himself as the candidate who will "drain the swamp," but his post-treasurer electoral track record isn't inspiring: He lost GOP primaries for governor in 2018, U.S. House in 2020 and lieutenant governor in 2022. Helgelien left the state legislature in 2012, but she does have endorsements from Trump acolytes like Roger Stone and hard-right Republican Reps. Paul Gosar of Arizona and Anna Paulina Luna of Florida.

—Geoffrey Skelley, 538

Trump loves to toot his own horn when it comes to his track record on endorsing winning candidates, and he'll be pleased with tonight's showing so far. Of the nine races where he has endorsed a candidate and we currently have results, Trump's picks have won six, are leading in two and are going to a runoff in one district, with his endorsee projected to finish in the top two. However, two of those six winning races were uncontested and five are incumbents (four incumbents are projected to win and one is currently leading), which makes his knack for picking winners look less like a Midas touch and more like just common sense. Still, in some of the more competitive races tonight, like South Carolina's 3rd District, which is going to a runoff, Trump's pick has performed well, so it's not all just obvious choices.

—Kaleigh Rogers, 538

We're about 20 minutes out from polls closing in Nevada, so let's take a look at some of the key races happening there tonight.

Nevada will hold a pivotal Senate contest this fall for the seat held by Democratic Sen. Jacky Rosen. Retired U.S. Army Capt. Sam Brown is the front-runner in the Republican primary, having established himself by finishing second for the GOP nomination in Nevada's 2022 Senate race. Brown's candidacy is highlighted by his military service record, during which time he suffered third-degree burns from a 2008 roadside bomb explosion in Afghanistan. Brown has proved a prodigious fundraiser, having brought in $7.1 million as of May 22. Former Ambassador to Iceland Jeffrey Ross Gunter, who served under Trump, is Brown's main competition, and he's self-funded $2.7 million of the $3.3 million he's raised.

National Republicans have largely consolidated behind Brown, including the National Republican Senatorial Committee. Brown and the NRSC have run joint ads focused on immigration and national security, and Rosen's campaign is already running spots against him focused on abortion rights. For his part, Gunter has linked himself to Trump, though Trump made a last-minute endorsement of Brown Sunday night, and has run ads claiming Brown backs the controversial-but-stalled plan to store nuclear waste at Yucca Mountain. Brown expressed support for the plan during his 2022 bid, but has backtracked in the face of criticism this time around.

It's unclear how big a threat Gunter is to Brown, as an early June survey from Noble Predictive Insights found Brown ahead 53 percent to 15 percent. But Gunter released a late May survey by Kaplan Strategies that found him running about even with Brown at around 30 percent. Outside groups have come in big for Brown to the tune of $4.3 million, and Gunter is enough of a danger that the pro-Brown Duty First Nevada super PAC is running ads portraying Gunter as a fake Republican. Still, Gunter's campaign actually canceled some ad buys ahead of the primary — not exactly a signal of confidence.

—Geoffrey Skelley, 538

Also on the ballot tonight in North Dakota: a ballot measure that would block anyone from being elected or appointed to the House or Senate from the state if they would turn 81 before their term ended. With 19 percent of the expected vote reporting, the measure is currently supported by 62 percent of the electorate. If the results hold, it would become the first state in the nation with a maximum age for elected office.

The only preelection polling we saw on this measure came from RMG Research/U.S. Term Limits in April/May, and showed voters in support of the measure by 65 percentage points, 78 to 13 percent. So while the measure may be somewhat underperforming, it's still on track to become the law of the land in North Dakota — if it can survive the inevitable legal challenges.

—Mary Radcliffe, 538