Mark Sanford vs. Katie Arrington: LIVE South Carolina primary election results

In South Carolina's 1st Congressional District, Freedom Caucus member Rep. Mark Sanford, R-S.C., is facing a tough primary challenge, perhaps the toughest of his political career.

Sanford, who was elected to the House of Representatives in 2013, was most recently polling at a statistical tie with his challenger, state Rep. Katie Arrington. In response, Sanford has spent more than $380,000 on advertising in his district, an unusual move for a congressman known to despise spending money.

Arrington has criticized Sanford for making disparaging remarks towards President Trump and for spending too much time on cable news. She has sought to brand Sanford, who labeled Trump's tariff policies as "an experiment with stupidity," as a NeverTrumper.

Dimitri Cherny is also running.

South Carolina is an open primary state, meaning voters do not need to register with a political party to vote in that party's primary election. The polls close at 7:00 p.m. ET.

Live results:

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