COLUMBIA, S.C. — Tuesday's South Carolina primary results reflected the strong support here for President Donald Trump, whose endorsements and name played a role in at least three races, political experts said.
Gov. Henry McMaster, who Trump endorsed, collected 42 percent of the vote and is headed for a runoff, while U.S. Rep. Mark Sanford, whom Trump opposed, was defeated by state Rep. Katie Arrington in the Republican race for the 1st congressional district.
And in the 4th district GOP contest, third-party ads attacked state Sen. William Timmons and state Rep. Dan Hamilton, both of Greenville, for once saying critical things about Trump. Hamilton missed the cut for a runoff in the race and Timmons placed second to former state Sen. Lee Bright.
"I think President Trump's support did have some impact on yesterday's primaries," said Robert Oldendick, a University of South Carolina political science professor. "It seems like the Trump presidency is one where people who are Trump supporters are completely loyal to him."
Both he and Chip Felkel, a Greenville GOP political consultant, agreed that Trump's voice was felt most in the 1st District race, where Arrington defeated Sanford, who had never lost a race before, after a last-minute tweet by Trump.
"Mark Sanford has been very unhelpful to me in my campaign to MAGA. He is MIA and nothing but trouble. He is better off in Argentina," Trump tweeted. "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!"
The Argentina reference concerned Sanford's extramarital affair with an Argentine woman while he was governor, which he publicly acknowledged in 2009.
Sanford had been a critic of Trump's presidency and Arrington raised that as an issue in her campaign.
Wednesday, on Fox News Channel's The Story with Martha MacCallum, Sanford said, "I wouldn't say it was the tweet, but the race, it was reduced down to who was more Trump versus not. And I lost that race."
Sanford went on to point out he had voted with the president 89 percent of the time.
"And so, I think it's important for all of us to stop and say, wait a minute, we have an institution set up by the Founding Fathers, where vigorous dissent, disagreement was part of what they set up. They wanted it to be a legislative branch — at times to be a check on the executive branch and vice versa.
"And if we lose that, if simply the litmus test of our elections is, who is 100 percent in allegiance with somebody else, I think we will lose ... an awfully important part of what makes our country special and unique based on the Founding Fathers’ design."
Felkel said had Trump not been president, Sanford likely would have won re-election. And McMaster, the first statewide elected official in South Carolina to endorse Trump for president while he was lieutenant governor, might not have ever become governor, he said.
With 97.8 percent of precincts reporting, Arrington collected 50.56 percent of the vote to Sanford's 46.49 percent, according to the State Election Commission's unofficial returns.
Oldendick said Arrington campaigned on Sanford's criticism of Trump, which "really kind of put things over the top."
"It's not an isolated issue," he said. "We've seen this in earlier races in earlier primaries."
Trump congratulated Arrington Wednesday morning in a tweet.
"My political representatives didn’t want me to get involved in the Mark Sanford primary thinking that Sanford would easily win — but with a few hours left I felt that Katie was such a good candidate, and Sanford was so bad, I had to give it a shot," Trump tweeted. "Congrats to Katie Arrington!"
Not everyone agrees that Sanford lost because of Trump.
"Sanford’s loss is not necessarily due to his problems with Trump, even if he claims it is because of him," said Adam Chamberlain, a Coastal Carolina University political science professor. "His past indiscretions could have played a role, absent criticisms from the president of the United States.
"Furthermore, it could also be that primary voters liked Katie Arrington’s approach, though I have no empirical evidence to back this up at this time. In other words, it is certainly possible that Sanford’s anti-Trump position mattered, but other factors might have played a role as well."
Bruce Ransom, a Clemson University political science professor, said it is possible Trump's last-minute endorsement carried Arrington over the top. But he said it is also possible her campaign was responsible. He said the problem with determining the influence of an endorsement is the lack of empirical evidence.
In the governor's race, McMaster frequently mentioned not only Trump's endorsement but also the actions he has taken as governor that mirror the president's, including positions on immigration and Planned Parenthood.
McMaster collected 42.31 percent of the vote, compared with 27.84 percent for John Warren, 21.39 percent for Catherine Templeton, 6.73 percent for Lt. Gov. Kevin Bryant and 1.73 percent for former Lt. Gov. Yancey McGill.
Felkel said he believes if not for Trump, McMaster would have finished in the 30s instead of the 40s.
"He made his margin over Warren and Templeton, I think, greater than it might have been without that support," Oldendick said of Trump.
But Chamberlain said he has yet to be convinced.
"Henry McMaster has a long history with the Republican Party in the state, but his earlier bid for governor in 2010 fell short," he said, referring to McMaster's third-place finish in that primary, far behind front-runner Nikki Haley, who won a runoff against Gresham Barrett.
"This said, he did get a plurality of the votes this election," Chamberlain said. "In states without a runoff, he would have won outright."
Though McMaster is in a runoff, Ransom said, Warren's success outside the Upstate is an open question, since he carried only Greenville and Pickens counties, he said. But it remains unclear, he said, what impact Trump may have had in the race.
Nonetheless, Felkel said, he expects McMaster to mention Trump a lot during the runoff.
In the 4th District race, both Timmons and Hamilton were attacked in a series of third-party ads over comments they once made about Trump.
Timmons finished the night with 19.20 percent of the vote, while Hamilton had 18.64 percent and Bright had 24.93 percent.
Felkel said there were so many candidates in the GOP race for the 4th District that Bright, who has a core group of supporters, exploited the numbers in much the same way Trump did when he ran for president in a crowded GOP field.