10 primaries to watch in South Carolina, North Dakota, Maine and Nevada

Tuesday is primary day in four states, and as always, 538 is keeping a close eye on the day's key competitive races. Every single one of our 10 elections to watch is a Republican primary, but they're split into two categories. In South Carolina and North Dakota, five contests for the U.S. House of Representatives and governor are all-but-guaranteed to decide the eventual November winner on solidly red turf. By comparison, Maine and Nevada have an array of five Republican primaries for the U.S. Senate and House in competitive seats currently held by Democrats that the GOP hopes to flip this fall.

You can get caught up on all these races here, and you can tune in to our liveblog Tuesday evening to follow the action as it happens, where we'll be tracking the ins and outs of these 10 primaries and anything else that pops up on our radar as the votes come in.

South Carolina

Races to watch: 1st, 3rd and 4th congressional districts

Polls close: 7 p.m. Eastern

The most-watched South Carolina race is in the 1st District, where second-term Republican Rep. Nancy Mace is defending her Lowcountry-based seat against a primary challenge from former state cabinet official Catherine Templeton. Mace sparked anger among some in the GOP last fall after she joined with seven other Republican House members to back the motion to vacate that ousted then-Speaker Kevin McCarthy. Her support came as a surprise because McCarthy had backed her in 2020 when she first ran here, but the move fit into her idiosyncratic track record as a onetime-ally of the old school GOP establishment who has evolved into an anti-establishment, Trump-minded conservative, at least in her rhetoric. That shift may also reflect a self-preserving political recalibration after redistricting made her once-competitive seat redder ahead of the 2022 election.

But the strategy could have its pitfalls: In Templeton, Mace has an establishment-aligned opponent who previously served in then-Gov. Nikki Haley's cabinet before mounting a failed gubernatorial bid in 2018. And while Mace has substantially outraised Templeton — $2.3 million to $663,000 as of May 22 — Templeton has received ample outside support. Groups have spent $5.3 million backing Templeton or attacking Mace, according to OpenSecrets, compared with $2.6 million supporting Mace or criticizing Templeton. Notably, some pro-Templeton money may have come from sources allied to McCarthy, and Mace has denounced Templeton as McCarthy's "puppet." The McCarthy-aligned American Prosperity Alliance is running ads against Mace, and reporting by the Charleston Post and Courier found that the brand-new South Carolina Patriots PAC — which has spent $3.8 million to boost Templeton — received a small amount of money from the APA. SCP has run ads that argue Mace is weak on border security, while Templeton has played up her conservative business and immigration bona fides.

However, Mace may have the ultimate, er, trump card: Former President Donald Trump has endorsed her, a development Mace and her allies, such as Club for Growth Action, have emphasized in campaign ads. This reflects the incumbent's shifting positions, especially considering Trump endorsed Mace's primary challenger in 2022, whom Mace narrowly defeated. Still, Trump's support may not be an unalloyed positive: The 1st District is the only one Haley carried versus Trump in South Carolina's February presidential primary.

Limited public polling suggests Mace is more likely than not to survive. An early May survey by Kaplan Strategies found Mace leading Templeton 43 percent to 21 percent, while a late May poll from Emerson College/The Hill put Mace ahead 47 percent to 22 percent. But there's a small chance that this race could go to a June 25 runoff, as a third Republican candidate could win enough votes to keep Mace or Templeton from winning a majority.

In the solidly red 4th District around Greenville, third-term Rep. William Timmons is another Republican incumbent dealing with a high-profile primary challenger. Though Timmons is a reliable conservative, state Rep. Adam Morgan could successfully run even further to Timmons's right, seeing as he chairs the state House's Freedom Caucus — modeled after the congressional caucus, whose membership encouraged Morgan's bid and whose campaign arm has endorsed him. Moreover, Timmons still seems to be plagued by a scandal that jeopardized his reelection bid two years ago: In 2022, amid allegations that Timmons was unfaithful to his wife, he only won renomination with 53 percent against weak primary opposition despite the fact his district barely changed in redistricting.

One sign that Timmons is feeling the heat is that he's done something unusual in a GOP primary: He's attacked his opponent for being too extreme on abortion rights, running an ad criticizing Morgan for voting "to jail rape and incest victims" who sought abortions — a vote Morgan has defended as "an attempt to close a loophole." Timmons's maneuver could be an attempt to draw Democratic and independent votes in South Carolina's open primary system, even though the incumbent supports a 15-week federal abortion ban.

Timmons still has some notable advantages working for him. He's outraised Morgan $1.9 million to $578,000, helped out by a $900,000 loan to his campaign (Morgan has self-funded nearly half his campaign, too). Outside groups, mainly the pro-cryptocurrency Defend American Jobs super PAC, have spent $1.9 million to boost Timmons, compared with just $319,000 in outside spending supporting Morgan. And here, too, Trump has endorsed the incumbent, which Timmons and his allies have played up in campaign ads. Still, Morgan has emphasized his Republican bona fides, pitching himself as a Christian and "conservative fighter" in his ads. We've seen no public polling here, so it's hard to know how close this race truly is.

The strongly Republican 3rd District next door features an open-seat race following the retirement of Republican Rep. Jeff Duncan, who also faced accusations of marital infidelity. In the GOP primary to succeed Duncan, the most notable contenders appear to be pastor Mark Burns, Air National Guard Lt. Col. Sheri Biggs and state Rep. Stewart Jones, but it's difficult to identify a favorite — or differentiate between them, as all three candidates have made the case that they're the most conservative, Trump-minded choice. On the fundraising front, Biggs had raised $528,000 as of May 22, while Burns had brought in $516,000, both largely through self-funding. Jones, meanwhile, had raised $217,000 with less self-funding, having represented a part of this region in the state legislature since 2019.

There's been comparably less outside intervention here, highlighted by the Sen. Rand Paul-associated Protect Freedom PAC's $670,000 outlay to help Jones and Elect Principled Veterans Fund's $314,000 to support Biggs. But it's Burns who has garnered Trump's critical endorsement. Burns's political profile as a pro-Trump Black televangelist has grown in recent years, including a second-place finish in the 4th District's 2022 primary. But he's attracted controversy, too, including in 2016 when he retweeted a fake photo of Hillary Clinton in blackface, and in 2022 when he called for the execution and arrest of those who support protecting transgender children. For her part, Biggs has the support of Republican Gov. Henry McMaster, while Jones gained notice for his efforts to dismantle COVID-19 pandemic-related restrictions. A runoff seems like a real possibility: The only public poll was a mid-May survey by Cygnal on behalf of the pro-Biggs Elect Principled Veterans Fund, which found all three contenders hovering around 10 percent.

Maine

Races to watch: 2nd Congressional District

Polls close: 8 p.m. Eastern

Maine's 2nd District is host to a GOP primary in which two first-term state representatives, Austin Theriault and Mike Soboleski, are contending for the right to take on three-term Democratic Rep. Jared Golden. The incumbent has managed to hold onto this seat, which takes in most of Maine north of its southern coastal area, despite its slight Republican lean: Trump would have carried it 51 percent to 45 percent in 2020, according to Daily Kos Elections, making it the second-most Republican-leaning seat (by presidential vote) that a Democratic incumbent is defending in 2024, trailing only Rep. Mary Peltola's at-large seat in Alaska.

Theriault, a former NASCAR driver, looks to be favored. He has Trump's endorsement, which he's naturally emphasized in his ads, and he's congressional Republicans' top choice, having earned the backing of Speaker Mike Johnson and the Congressional Leadership Fund, the principal super PAC involved in supporting Republican House candidates. Moreover, Theriault has raised $1.2 million to Soboleski's $117,000. The only somewhat recent poll was an early April survey from Public Opinion Strategies on behalf of Theriault's campaign that found him leading Soboleski 30 percent to 7 percent. But while Theriault has Trump's backing, Soboleski aligns with the former president — and around two-thirds of Republicans nationally — on the question of the 2020 election's legitimacy. Unlike Theriault, Soboleski has echoed Trump's unsupported claim that Biden didn't legitimately win.

North Dakota

Races to watch: At-Large Congressional District; governor

Polls close: Generally 8 p.m. Eastern in most of the state, 9 p.m. Eastern in southwestern counties

North Dakota Gov. Doug Burgum's retirement has precipitated an expensive and increasingly ugly Republican primary for governor between Rep. Kelly Armstrong and Lt. Gov. Tammy Miller. Armstrong is more familiar to voters, having served in Congress since 2019, while Burgum tapped Miller as his new lieutenant governor in December 2022 (after the previous officeholder resigned to return to the private sector). Both candidates have thrown around large sums of their own money: Based on financial reports though May 2 and large donations reported through June 7, about $3.8 million of the $4.2 million Miller has reported raising has come out of her own pocket, while Armstrong has self-funded almost $1.3 million of the $3.4 million he's collected.

Armstrong is the front-runner, having garnered endorsements from Trump and the state GOP. He also held a clear lead in three different surveys conducted in May, all of which showed him receiving close to 60 percent while Miller only attracted around 20 percent. Looking to gain ground, Miller has tried to link herself to Trump and Burgum, who's endorsed her. She's also run negative ads against Armstrong, including one that Rob Port of InForum described as "the most brutal" he'd seen in North Dakota that accuses Armstrong of insider trading and defending a child molester when he was a lawyer. Armstrong's campaign called the insider trading claim a lie, and the victims in the molestation case called for Miller to stop running ads about it. And Armstrong isn't without his own ad controversy, as his campaign ran a spot against Miller that included a citation from an artificial intelligence news website, which prompted Miller to criticize Armstrong for running "fake news" about her record.

Armstrong's gubernatorial bid has left the state's At-Large Congressional District up for grabs, and the two main contenders in the Republican primary look to be Public Service Commissioner Julie Fedorchak and former state Rep. Rick Becker. Fedorchak has a solid electoral record, having won three statewide races to retain her current office, and she earned Trump's endorsement in late May. Meanwhile, Becker has a complicated relationship with the GOP: During his legislative tenure, Becker founded a far-right caucus, and in 2022, he actually ran for Senate as an independent against Republican Sen. John Hoeven. That campaign left Becker ineligible for the state GOP endorsement vote in April, but his supporters spoiled their ballots to give the endorsement to a minor candidate instead of Fedorchak.

Meanwhile, Becker and his allies have mostly kept up with Fedorchak in the money race. Fedorchak has brought in $979,000, compared with Becker's $911,000, although Becker self-funded $550,000 of his haul. Yet outside groups have spent slightly more promoting Becker or attacking Fedorchak ($1.5 million) than on supporting Fedorchak or opposing Becker ($1.3 million). Both candidates have emphasized their pro-Trump views and plans to secure the border. Two surveys have shown a close race, too: An early May poll from DFM Research/North Dakota United put Becker ahead 29 percent to 26 percent, while a late May survey from WPA Intelligence/North Dakota News Cooperative found Fedorchak leading 32 percent to 25 percent. However, both polls predated Trump's endorsement, and, in a possible signal that Fedorchak has the upper hand, the pro-Becker Club for Growth canceled a planned ad buy for the final week of the campaign.

Nevada

Races to watch: U.S. Senate; 1st, 3rd and 4th congressional districts

Polls close: 10 p.m. Eastern

Nevada will hold a pivotal Senate contest this fall for the seat held by Democratic Sen. Jacky Rosen, who is seeking a second term. 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. Trump has notably not endorsed in this race, though on Sunday he complimented Brown and seemed to acknowledge his frontrunner status, For his part, Gunter has linked himself to Trump, 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, similar to the results in a mid-May survey conducted by the Tarrance Group for Brown's campaign and the NRSC. 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 $4.2 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.

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.

Next door, Democratic Rep. Steven Horsford will be defending the blue-leaning 4th District, and the two principal GOP contenders are retired Air Force Lt. Col. David Flippo and former North Las Vegas Mayor John Lee. Flippo has raised $927,000 to Lee's $851,000 — both candidates have self-funded more than half of their totals — but Lee may have the upper hand here, thanks to endorsements from Trump and Lombardo. However, Lee is a former Democrat who switched parties ahead of a failed bid for the Republican nomination for governor against Lombardo in 2022, which could weaken his appeal among primary voters.

Lastly, there's a GOP primary to monitor in the 1st District, another light-blue seat in and around Las Vegas held by Democratic Rep. Dina Titus. In the 2022 general election, Titus defeated Army veteran Mark Robertson by nearly 6 percentage points, but Robertson is back for another go. However, he's only raised $106,000, a figure dwarfed by restaurateur Flemming Larsen, a GOP rival who has brought in a whopping $1.8 million thanks to $1.5 million in self-funding. It's unclear if a recent report by the Nevada Independent disclosing that Larsen hired undocumented immigrants at his southern California restaurants will notably impact the race.