Columbia, SC (AP) - Incumbent Henry McMaster has been forced into a runoff for the Republican nomination in South Carolina's gubernatorial primary.

McMaster was an early supporter of President Donald Trump, and he was the top vote-getter in Tuesday's primary. But he failed to win the 50 percent necessary to avoid a runoff. Now, he and Greenville businessman John Warren are headed for a second contest June 26.

MORE: South Carolina Primary Full Electon Results

The vote tested the heft of Trump's endorsement in South Carolina, where McMaster became governor last year following Nikki Haley's departure to serve as U.N. ambassador. As lieutenant governor, McMaster was the nation's first statewide elected official to back Trump ahead of South Carolina's early presidential primary.

McMaster was unsuccessful in his 2010 gubernatorial bid, losing a four-way primary to Haley. The GOP nominee faces Democratic state Rep. James Smith in November.