Trump and McMaster (copy) (copy)

Gov. Henry McMaster and President Donald Trump at a rally in South Carolina during the 2016 presidential campaign.  File/AP Photo/John Bazemore

President Donald Trump tweeted his support of Republican Gov. Henry McMaster Thursday morning, amplifying his long-standing endorsement for McMaster on social media days before his South Carolina visit to stump for the governor in-person.

"Henry McMaster has done a great job as Governor of South Carolina. The State is BOOMING, with jobs and new industry setting records. He is tough on Crime and strong on Borders, Health Care, the Military and our great Vets. Henry has my full and complete Endorsement!" the president tweeted with the #MAGA hashtag, an abbreviation of Trump's campaign promise to "Make America Great Again."

Trump also confirmed his plans to campaign for McMaster, saying in a separate tweet that he will be in Columbia on Monday night to "do a campaign speech for one of my very early supporters."

Vice President Mike Pence is also reportedly coming to South Carolina to stump for McMaster, the first time Pence has done so. A source has told The Post and Courier Pence is expected to campaign for McMaster Saturday in Myrtle Beach.

"Henry worked so hard & was so loyal to me that I look forward to reciprocating!" Trump tweeted.

McMaster was the nation's first statewide elected official to back Trump in his presidential bid. McMaster in 2016 officially nominated Trump for president at the Republican National Convention.

The tweets come five days ahead of McMaster's GOP runoff with Greenville businessman John Warren. 

About an hour after Trump tweeted his support, McMaster tweeted his thanks.

"I am honored by your friendship and support, Mr. President. On behalf of South Carolinians everywhere, we look forward to seeing you on Monday night!" McMaster said in his post.

McMaster's lieutenant governor pick, Pamela Evette, also retweeted both of the president's posts.

Trump had previously endorsed McMaster in the GOP governor's race. Trump in October headlined a fundraising dinner in Greenville for McMaster.

The social media backing for McMaster marks the second time in as many weeks that Trump has waded into political races playing out in the Palmetto State. 

In a late-afternoon tweet during the June 12 primary, Trump endorsed Katie Arrington, the Republican primary challenger who ran against incumbent U.S. Rep. Mark Sanford.

Arrington defeated Sanford in that primary election.

This is a developing story. Check back to Post and Courier for updates.

Reach Caitlin Byrd at 843-937-5590 and follow her on Twitter @MaryCaitlinByrd.

Caitlin Byrd is a political reporter at The Post and Courier and author of the Palmetto Politics newsletter. Before moving to Charleston in 2016, her byline appeared in the Asheville Citizen-Times. To date, Byrd has won 17 awards for her work.