He is a Baptist minister who opposes gay marriage, a Republican who is critical of his party’s leaders in Congress, and a candidate who ran a shoestring campaign against a House incumbent. And on Wednesday, Mark Harris found himself in another role: A giant-killer of the 2018 midterm elections.
Mr. Harris beat Representative Robert Pittenger in a Republican primary in North Carolina on Tuesday, making Mr. Pittenger the first incumbent from either party to lose his seat in Congress due to a primary challenger this year.
House Republicans were already concerned about Mr. Pittenger’s chances against the well-funded Democratic nominee, the Iraq war veteran Dan McCready, but believed he would fend off the challenge from Mr. Harris, who instead beat him by fewer than 1,000 votes.
“People are catching on to that ‘drain the swamp’ thing, and I think that is a message we have to consider,” Mr. Harris said in a telephone interview on Wednesday. “Is it fair to say the establishment was surprised by what happened last night? Definitely so.”
Mr. Harris, 52, will now face a Democrat whose campaign war chest vastly outmatches his own: Last month, Mr. McCready’s campaign had more than $1.2 million in the bank, while Mr. Harris had just $70,000. Mr. McCready beat a primary challenger of his own, Christian Cano, with more than 82 percent of the vote.
Mr. Harris, who nearly unseated Mr. Pittenger two years ago, won by portraying the three-term incumbent as a Washington insider who violated the spirit of a 2012 campaign pledge to support term limits. He also criticized Mr. Pittenger for his vote in favor of a $1.3 trillion spending bill, which was both signed and rebuked by President Trump in March.
A former president of the North Carolina Baptist Convention, Mr. Harris is a social conservative who helped lead a successful ballot initiative in 2012 that amended the state constitution to forbid North Carolina from performing or recognizing same-sex marriage or civil unions.
During the primary campaign, he said he would support the nomination of Supreme Court justices willing to revisit both Roe v. Wade, which legalized abortion in the United States, and Obergefell v. Hodges, the 2015 decision that legalized same-sex marriage nationwide. He also supported the construction of a border wall in the Southwestern United States and the repeal and replacement of the Affordable Care Act.
While President Trump told an interviewer after the 2016 election that the issue of same-sex marriage had “been settled and I’m fine with that,” Mr. Harris disputed the idea that the country had moved on.
“I think values and principles that people hold don’t change,” Mr. Harris said. “A lot of these things comeback to states’ rights and you’re going to see that with Roe v. Wade.”
Mr. Harris pointed to state-level initiatives to regulate in abortion, like one that recently advanced in Iowa, as an example of how opponents of same-sex marriage could confront the issue.
“You’re already seeing abortion laws passed in some states that will be challenged in court and you’ll see the same things with that issue,” he said. “These are states’ rights issues and we’ll have to wait and see how the various states deal with them.”
North Carolina’s 9th District, which stretches from Charlotte to Fayetteville, has traditionally been friendly ground for Republicans, but observers said the financial mismatch between the two opponents, coupled with anti-establishment political headwinds nationwide, could make it a tossup in November.
“This is great news for Dan McCready,” said Morgan Jackson, a Democratic strategist in North Carolina.
He also predicted that Mr. Harris’s history of conservative social activism would hurt him in the general election.
“He is a guy who is very far to the right, father to the right than this district is, but in order to motivate his base to turn out he has to tack to the right,” Mr. Jackson said. “If he tacks to the middle, he alienates his base. This is a turnout election, and he’s got problems both ways.”
Dallas Woodhouse, the executive director of the North Carolina Republican Party, said he thought the party would have stood roughly the same chance of winning with either Mr. Pittenger and Mr. Harris as its nominee. He said the financial disparity between Mr. Harris and Mr. McCready could be overcome by getting “some heavy hitters” to campaign in the district, which he hoped would include President Trump and Vice President Pence.
Mr. Woodhouse said he did not think the primary results held a larger message for the Republican Party at large. Like every other Republican primary in the state, he said, both candidates agreed on their support for President Trump.
“Everyone was trying to be more Trump, not less,” he said. That includes Mr. Harris and Mr. Pittenger. “They fell over themselves to embrace it. Absolutely.”