Lauren Boebert’s Rival, Adam Frisch, Concedes Their Colorado House Race

In one of the country’s closest House races, Adam Frisch, a Democrat challenging Representative Lauren Boebert of Colorado, a far-right gunslinger known for her provocations on Capitol Hill, said on Friday that he had called her to concede, as Ms. Boebert appeared increasingly likely to win a second term. The Associated Press has not called the contest.

Mr. Frisch, a Democratic businessman and former Aspen, Colo., city councilman, had put up a fierce challenge to Ms. Boebert, 35, who was seen as a heavy favorite entering the race in Colorado’s Republican-leaning Third Congressional District.

As of Thursday evening, according to The A.P., Ms. Boebert led by a mere 0.16 percentage points — or 551 votes of nearly 327,000 counted to date. Nearly all of the votes have been counted, according to The A.P. The margin qualifies for an automatic recount under state law, which would further delay an official race call.

“The likelihood of this recount changing more than a handful of votes is very small — very, very small,” Mr. Frisch said Friday in a video posted on Facebook. “It’d be disingenuous and unethical for us or any other group — any other group — to continue to raise false hope and encourage fund-raising for a recount. Colorado elections are safe, accurate and secure.”

Mr. Frisch had sought to cast Ms. Boebert as a flamethrower in an increasingly polarized Congress, who he said was more focused on placating the Republican Party’s far-right Trump wing than reducing inflation and adding jobs.

“I heard time and time again on the campaign trail, America is tired of the circus, tired of the lack of respect for our institutions and our democracy, and tired of the lack of civility in our discourse,” Mr. Frisch said in the video, suggesting that Ms. Boebert was part of the “angertainment industry.”

On Twitter, Ms. Boebert wrote that Mr. Frisch had called her to concede, saying: “I look forward to getting past election season and focusing on conservative governance in the House majority. Time to get to work!”

In a television ad presenting him as not a typical Democrat — it showed footage of Mr. Frisch hunting with a shotgun — he said that he would not vote for Representative Nancy Pelosi for House speaker and that he supported border security.

But a disadvantage in name recognition and the makeup of voters in the district proved an obstacle for Mr. Frisch against Ms. Boebert, who has drawn national attention for her fiery actions.

Along with Representative Marjorie Taylor Greene of Georgia, a fellow Republican also in her first term, Ms. Boebert brought a no-holds-barred brand of politics to the House, feeding off a social media echo chamber of loyalists to former President Donald J. Trump. That has put Ms. Boebert at odds with platforms like Twitter, which temporarily suspended her account after she spread the falsehood that the 2020 election was rigged.

Ben Shpigel contributed reporting.