Gov. Henry McMaster took a phone call from President Donald Trump during a press conference Monday in North Charleston, providing flashy proof of his direct line to the White House ahead of next week’s GOP runoff with Greenville businessman John Warren.

Both Republican candidates for governor have tried to play up their Trump credentials ahead of the June 26 vote. The attempts to out-Trump each other continued Monday.

For McMaster, the presidential phone call was a public reminder that Trump has already endorsed him formally and through two tweets.

The presidential call came about 13 minutes into a North Charleston press conference where 35 Lowcountry leaders announced they would be supporting McMaster.

The call was first answered by McMaster campaign spokeswoman Caroline Anderegg from across the room. She audibly said for the entire room to hear, "Yes, he's available."

Three seconds later, McMaster, who was not near the phone at the time said, "Oh, that’s the president — believe it or not."

It prompted a chuckle from McMaster’s supporters, including North Charleston Mayor Keith Summey, who moments earlier complimented McMaster for having contacts in Washington.

McMaster grabbed the phone, walked into an isolated room at the front of North Charleston City Council Chambers and said, "Hold tight. Hello!"

McMaster did not put the call on speaker phone while still in the room. He was gone for roughly 10 minutes.

Anderegg, McMaster’s campaign spokeswoman, said afterward the call from Trump was authentic. Asked if it the interruption was timed to happen during the presser, she said, "You know we can’t control what the president does."

The move came as earlier Monday, Republican U.S. Rep. Ralph Norman of Rock Hill endorsed Warren after previously backing Catherine Templeton in the GOP race.

"John Warren will shake up this system in Columbia," Norman said in a media release. "He fits right into the mold of President Trump: he’s a self-made man who understands business and he’s got the establishment politicians running for cover. John Warren will continue the work Nikki Haley started."

McMaster won in all 11 counties that make up or are part of the 5th Congressional District during the first round of voting on June 12, carrying between 50 and 67 percent of the vote.

Also endorsing Warren on Monday was state Sen. Wes Climer, R-Rock Hill, another early Templeton supporter.

The two Republicans will face each other in a televised debate at 7 p.m. Wednesday night in Newberry on SCETV and co-sponsored by The Post and Courier.

Reach Caitlin Byrd at 843-937-5590. Follow her on Twitter at @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.