Spiky tweet aimed at Mark Sanford, a vocal critic of the president, comes hours before polls close in South Carolina primary

Donald Trump launched an unusual attack against a sitting House Republican only hours before polls closed in Tuesday’s primary election.



Trump – flying back from Singapore on Air Force One – attacked Mark Sanford, a South Carolina Republican, urging voters to support his rival.

In his tweet, Trump said: “Mark Sanford has been very unhelpful to me in my campaign to MAGA. He is MIA and nothing but trouble. He is better off in Argentina. I fully endorse Katie Arrington for Congress in SC, a state I love. She is tough on crime and will continue our fight to lower taxes. VOTE Katie!”

The reference to Argentina stems from an extramarital affair that the libertarian Republican had in 2009 while serving as governor. Sanford, who was married, fell in love with an Argentinian woman, María Belén Chapur, and went to visit her after telling his staff that he would be “hiking the Appalachian trail”. He later described Chapur as his soul mate.

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Sanford, a member of the hard-right House Freedom Caucus, has long been one of the few congressional Republicans willing to openly break with Trump.

The result is that he has faced a primary challenge from Katie Arrington, a state representative who is campaigning on her loyalty to Trump.

Within minutes, the Arrington campaign was also blasting out a robocall touting Trump’s endorsement and encouraging voters to “get out and vote, even in the rain”.

Although Sanford backed key Republican priorities in Congress such as cutting taxes and healthcare, and has been endorsed by major conservatives groups such as the Club for Growth, he has also been vocal with his criticism of Trump when they have disagreed. He condemned Trump’s travel ban and support for increased tariffs. Sanford also said in a 2017 interview that Trump “has fanned the flames of intolerance”.

The South Carolina Republican, who served in Congress from 1995-2001, was re-elected in 2013 in a special election in his Charleston-based district. Trump won the district in 2016 by a margin of 53% to 40%.

Sanford did not immediately respond to a request for comment.

In a statement, Mike Biundo, a consultant for Arrington’s campaign and a veteran Republican operative, said: “The president’s endorsement is very important. The president’s record of keeping his promises resonates across the district. Katie has spent months working to tell the voters of South Carolina just how much that Mark Sanford has done to work against the president and his agenda. This amplifies that and solidifies our message.”

Other Republicans rallied to Sanford’s defense. Mark Meadows, the chair of the Freedom Caucus and a Trump confidant, said in a statement: “Mark Sanford has been a valued member of the Freedom Caucus and certainly has been a thoughtful member of Congress. I am very supportive of his re-election efforts and passage of the tax reform package would not have been possible without his input.”

A spokesman for the House speaker, Paul Ryan, told the Guardian that “the speaker supports Mark Sanford in the race tonight. This keeps with his policy to support all GOP incumbents running for re-election.”

The Republican congressman Justin Amash, a fellow libertarian-leaning Trump critic, also tweeted his support for Sanford, in a message aimed at Trump, writing: “He’s one of the most principled, consistent, and conservative members of Congress I’ve ever known. And unlike you, Mark has shown humility in his role and a desire to be a better man than he was the day before.”

