It’s election day for the primaries in South Carolina, and President Donald Trump has a message for Republican voters: Don’t vote for incumbent Rep. Mark Sanford.

Trump endorsed Sanford’s far-right primary challenger Katie Arrington at 4:12 pm — three hours before polls close — in a tweet Tuesday that also dug up Sanford’s past scandal.

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! — Donald J. Trump (@realDonaldTrump) June 12, 2018

You may remember Sanford from his sex scandal during his time as South Carolina’s governor. Sanford mysteriously disappeared from the governor’s office for a week in 2009, during which time his office said Sanford was “hiking the Appalachian Trail.” But Sanford later admitted he was in Buenos Aires with an Argentine journalist he was having an extramarital affair with — hence Trump’s comment that Sanford was “better off in Argentina.” He resurfaced in 2012 to run for the House, and won.

In the House, Sanford is a member of the conservative House Freedom Caucus, but he’s a comparatively moderate House GOPer and has been known to openly criticize Trump and at times the Republican agenda. He’s voted with Trump 73 percent of the time.

Newly Trump-endorsed state lawmaker Arrington is running a campaign to the far right of Sanford, portraying him, as Politico put it, as “a disloyal Never Trumper.”

This race popped up on the radar when Politico reported Sanford was going on TV to attack Arrington, which suggested he felt some heat. He wouldn’t be the first House Republican to struggle in 2018 for being insufficiently loyal to the president.

It would take a major Democratic wave for the district to become competitive in November, though Cook rates it as merely Likely Republican, rather than Absolutely Without a Doubt Republican.

Trump’s margin of victory in 2016 was narrower than Mitt Romney’s in 2012, but he still won the district by 13 points. Cook rates it as an R+10 district. But it’s possible things could get wild if Sanford falls in Tuesday’s primary.