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. 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.

—Geoffrey Skelley, 538

As usual, tonight we'll be watching to see how candidates endorsed by Trump fare in their respective races. The former president loves to tout his "very unblemished" track record for endorsing candidates who win, though when you take a closer look at his numbers, it's not always that impressive. Still, Trump's seal of approval can often be enough to give an edge in a tight primary race, so we'll be watching the 11 races tonight where he has endorsed a candidate:

Trump has already won in two of today's races, since he endorsed incumbents North Dakota Sen. Kevin Cramer and South Carolina Rep. Russell Fry, each of whom are running unopposed. He'll also likely have luck with the other two incumbents he endorsed, Reps. Nancy Mace and William Timmons in South Carolina, though they're facing challengers. As for non-incumbents, Trump made a last-minute endorsement of retired U.S. Army Capt. Sam Brown, who's enjoyed strong party backing and is heavily favored to win. His pick in Maine's 2nd District, former NASCAR driver state Rep. Austin Theriault, also seems to be favored to win, as does former North Las Vegas Mayor John Lee in Nevada's 4th District.

But Trump has had a few disappointments in recent weeks. Mendham Mayor Christine Serrano Glassner, whom Trump endorsed for the GOP Senate primary in New Jersey, lost by 7 percentage points last week, and his endorsee for Texas's 21st State House District narrowly lost his primary in a May 28 runoff. I'll be keeping an eye on these races as results come in tonight, and will keep you updated on how blemished or unblemished Trump's record remains.

—Kaleigh Rogers, 538

The strongly Republican 3rd District in Upstate South Carolina 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. 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.

Outside spending here has come principally via 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 Burns has 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.

—Geoffrey Skelley, 538

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.

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 $327,000 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.

—Geoffrey Skelley, 538