COLUMBIA, S.C. — Rep. Mark Sanford, a vocal critic of President Donald Trump, lost his South Carolina congressional seat hours after the president injected himself into the bitter Republican primary by stoking memories of the incumbent's public extramarital affair several years ago.

In the most dramatic result in primaries across five states Tuesday, Sanford was the second incumbent House Republican to lose a primary this year — the latest victim of intense divisions among the GOP in the Trump era. Though he has a generally conservative voting record, his criticism of Trump as unworthy and culturally intolerant made him a target of the president's most dedicated supporters, who often elevate loyalty over policy.

Sanford was defeated by state Rep. Katie Arrington , who spent her campaign blasting Sanford as a "Never Trumper." And hours before polls closed, Trump posted a startlingly personal attack on Twitter, calling Sanford "very unhelpful."

"He's MIA and nothing but trouble," Trump continued. "He is better off in Argentina."

The swipe was a reference to Sanford's unexplained disappearance from the state in 2009, which he later said was part of an affair he was carrying on with a woman in Argentina.

Even for a political figure with no shortage of confidence wading into his own party's decision-making, Trump's attack on Sanford was a bold case of going after a sitting member of Congress. It's almost certain to make other Republicans even more reluctant to take him on, even as Trump has stirs division on trade, foreign policy and the Russia investigation.

In his remarks Tuesday night, Sanford was unbowed, saying, "I stand by every one of those decisions to disagree with the president."

Sanford had never lost a political race in South Carolina and his defeat Tuesday was an abrupt end to a roller-coaster political career that included a resignation as South Carolina's governor following his admission of the affair.

After declaring victory Tuesday, Arrington asked Republicans to come together. And she reminded them who she thinks leads them: "We are the party of President Donald J. Trump."

Four other states voted Tuesday, including several races that will be key to determining which party controls the House of Representatives next year.

In other races:

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IN SOUTH CAROLINA, INCUMBENT GOVERNOR FACES RUN-OFF

Sanford was not the only establishment Republican to face a challenge Tuesday. South Carolina Gov. Henry McMaster, a close ally of Trump, was forced into a runoff after failing to muster the required 50 percent vote to win outright.

McMaster, an early supporter of the president's 2016 campaign, had Trump's full endorsement, marked by a weekend tweet.

But while Trump remains very popular in the state, McMaster has been shadowed by a corruption probe involving a longtime political consultant. McMaster received the most votes of the four Republicans running, but will face Greenville businessman John Warren in a second contest June 26.

McMaster, the former lieutenant governor, assumed the governorship last year after Nikki Haley resigned to become U.S. ambassador to the United Nations.

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GOP'S 'VICIOUS' VIRGINIA VICTOR

In a big Virginia race , Republican Corey Stewart — known for his ardent defense of Confederate symbolism — won the Republican primary to face Democratic Sen. Tim Kaine.

Stewart surprised many by nearly winning last year's Republican nomination for governor.

He was the top aide to Trump's presidential campaign in Virginia in 2016, but was fired for staging an unauthorized protest of the Republican National Committee. Stewart had accused the party of inadequately defending the candidate after the release of a tape where Trump bragged about groping women.

As a candidate for governor in 2017, Stewart spoke out against removing Confederate monuments, including the Robert E. Lee statue that prompted a deadly protest in Charlottesville last year. Stewart called efforts to remove the monuments "an attempt to destroy traditional America."

He said Tuesday he planned to wage a "vicious" campaign against Kaine.

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A HOUSE BELLWETHER IN VIRGINIA

Democratic State Sen. Jennifer Wexton was the clear winner in a six-way primary in a northern Virginia district considered key to the House battleground map this fall, and will challenge Republican Rep. Barbara Comstock.

Democrats in two other districts they hope to retake nominated women: Abigail Spanberger in central Virginia and Elaine Luria in the district that includes Virginia Beach.

In Comstock's district, Wexton was the best-known in the field, and was viewed as the Democratic Party's establishment choice. She had the endorsement of Democratic Gov. Ralph Northam.

Comstock, a moderate Republican who easily beat back a challenge from conservative Shak Hill, is one of the Democrats' top targets in November. The second-term House member's district leans Republican, though Democrat Hillary Clinton received more votes there than Trump did in 2016.

Though Wexton favors a ban on the sale of assault weapons, she defied what has been the tendency in some swing districts to nominate Democrats with liberal profiles on other key issues. She has not called for a single-payer, government-run health insurance system, as some Democratic House primary winners in California, Nebraska and Pennsylvania have.

Democrats need to gain 23 seats to win the majority in the House.

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TURNING THE LePAGE

Maine voters are deciding on a successor to term-limited, conservative Republican Gov. Paul LePage. But first they had to wrestle with a new balloting system. Maine on Tuesday debuted its statewide ranked-choice voting , which allows voters to rank candidates first to last on their ballot.

The system insured that counting was slow and winners difficult to call. But businessman Shawn Moody won the GOP nomination after midnight. He maintained a wide lead through the night, but risked not winning the race outright under the new rules.

The Associated Press did not call the Democratic primary as none of the seven candidates was close to the majority needed to be declared the outright winner, so more tabulations are required next week under ranked-choice voting. Last-place candidates will be eliminated and votes reallocated until there is a winner, a process that may take more than a week.

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NEVADA, NORTH DAKOTA: SEE YOU IN NOVEMBER

Nevada and North Dakota are home to two of the most pivotal Senate races this year. What they didn't have were competitive Senate primaries.

Nevada Sen. Dean Heller, the only Republican seeking re-election in a state that Hillary Clinton carried in 2016, and Democratic Rep. Jacky Rosen sailed through their primaries, and already have begun focusing their criticism on each other in what is expected to be among the most competitive Senate races this year.

There was also the return of Sharron Angle , the conservative who once ominously threatened to "take out" then-Sen. Harry Reid. Angle, who lost to Reid in her 2010 bid for Senate, lost her primary challenge to Rep. Mark Amodei on Tuesday.

Centrist Steve Sisolak won a bruising battle between Clark County commissioners vying to be Nevada's first Democratic governor in two decades. Fellow board member Chris Giunchigliani ran as a progressive, knocking Sisolak for his positive rating from the National Rifle Association in light of the mass shooting in Las Vegas in October. Republican Attorney General Adam Laxalt easily cleared the GOP field.

Nevada election officials blamed new touch-screen voting machines for glitches that affected a small number of voters and delayed the count of ballots in rural Pershing County. In no case were voters unable to successfully cast a ballot, the Nevada Secretary of State's office said.

In North Dakota, GOP Rep. Kevin Cramer will face moderate Democratic Sen. Heidi Heitkamp . She is seeking re-election in a state Trump carried by 36 percentage points in 2016.

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BROTHELS ON THE BALLOT

Pimp Dennis Hof, the owner of half a dozen legal brothels in Nevada and star of the HBO adult reality series "Cathouse," won a Republican primary for state Legislature, ousting a three-term lawmaker.

Voters in November will also be voting on closing down brothels in at least one of the seven Nevada counties where they're legally operating, and activists are trying to get the measure on the ballot in another district.

Associated Press writers Meg Kinnard and Christina Myers in Columbia, S.C.; Marine Villeneuve in Augusta, Maine; Patrick Whittle in Portland, Maine; Alan Suderman in Richmond, Va.; Matthew Barakat in McLean, Va.; Scott Sonner in Reno, Nev.; Michelle Price in Las Vegas; and James MacPherson in Bismarck, N.D., contributed to this report.