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Trump endorses GOP Rep. Mark Sanford's primary challenger

Last Updated Jun 13, 2018 3:03 AM EDT

President Trump endorsed incumbent GOP Rep. Mark Sanford's primary challenger Katie Arrington in a tweet sent from Air Force One on Tuesday with just hours left to vote in South Carolina. Sanford went on to lose.

"Mark Sanford has been very unhelpful to me in my campaign to MAGA," Mr. Trump tweeted on his way home from his summit with North Korean Dictator Kim Jong-Un in Singapore. 

"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!," Mr. Trump added, referring to Sanford's infamous 2009 trip to Argentina when he tried to secretly visit his mistress while he was governor. At the time, he claimed he had been hiking on the Appalachian Trail.

After his term ended, he ran and won a seat in the House in 2013. Since Mr. Trump has been in office, Sanford has been a vocal critic. Recently, he told the Weekly Standard that the aluminum and steel tariffs were "disastrous" and said of them that "our country seems to experiment with stupidity every 100 years as it relates to trade."

Arrington has capitalized on Sanford's opposition toTrump during his time in office — calling him a "never Trumper" throughout her campaign — and has also taken digs at Sanford's past scandal in campaign ads. 

".@MarkSanford's job is to support and defend the Constitution. He's one of the most principled, consistent, and conservative members of Congress I've ever known," Sanford's colleague from Michigan, Representative Justin Amash, quickly fired back at Trump on Twitter. "And unlike you, Mark has shown humility in his role and a desire to be a better man than he was the day before."

Trump continued his Twitter tear on his flight back to the U.S., taking aim at Robert DeNiro next. 

"Robert De Niro, a very Low IQ individual, has received to many shots to the head by real boxers in movies," Trump tweeted — presumably a delayed response to DeNiro's Sunday night speech at the Tony Awards. "I watched him last night and truly believe he may be "punch-drunk." I guess he doesn't…"

"...realize the economy is the best it's ever been with employment being at an all time high, and many companies pouring back into our country. Wake up Punchy!" he added.

The President also tweeted an update of his meetings in Singapore "after a truly amazing visit"and said that "great progress was made on the denuclearization of North Korea."