WASHINGTON — Calling former President Donald J. Trump “a cancer for the country,” Representative Anthony Gonzalez, Republican of Ohio, said in an interview on Thursday that he would not run for re-election in 2022, ceding his seat after just two terms in Congress rather than compete against a Trump-backed primary opponent.

Mr. Gonzalez is the first, but perhaps not the last, of the 10 House Republicans who voted to impeach Mr. Trump after the Jan. 6 Capitol riot to retire rather than face ferocious primaries next year in a party still in thrall to the former president.

The congressman, who has two young children, emphasized that he was leaving in large part because of family considerations and the difficulties that come with living between two cities. But he made clear that the strain had only grown worse since his impeachment vote, after which he was deluged with threats and feared for the safety of his wife and children.

Mr. Gonzalez said that quality-of-life issues had been paramount in his decision. He recounted an “eye-opening” moment this year: when he and his family were greeted at the Cleveland airport by two uniformed police officers, part of extra security precautions taken after the impeachment vote.

“That’s one of those moments where you say, ‘Is this really what I want for my family when they travel, to have my wife and kids escorted through the airport?’” he said.

Mr. Gonzalez, who turns 37 on Saturday, was the sort of Republican recruit the party once prized. A Cuban American who starred as an Ohio State wide receiver, he was selected in the first round of the N.F.L. draft and then earned an M.B.A. at Stanford after his football career was cut short by injuries. He claimed his Northeast Ohio seat in his first bid for political office.

Mr. Gonzalez, a conservative, largely supported the former president’s agenda. Yet he started breaking with Mr. Trump and House Republican leaders when they sought to block the certification of last year’s presidential vote, and he was horrified by Jan. 6 and its implications.

Still, he insisted he could have prevailed in what he acknowledged would have been a “brutally hard primary” against Max Miller, a former Trump White House aide who was endorsed by the former president in February.

Yet as Mr. Gonzalez sat on a couch in his House office, most of his colleagues still at home for the prolonged summer recess, he acknowledged that he could not bear the prospect of winning if it meant returning to a Trump-dominated House Republican caucus.

“Politically the environment is so toxic, especially in our own party right now,” he said. “You can fight your butt off and win this thing, but are you really going to be happy? And the answer is, probably not.”

For the Ohioan, Jan. 6 was “a line-in-the-sand moment” and Mr. Trump represents nothing less than a threat to American democracy.

“I don’t believe he can ever be president again,” Mr. Gonzalez said. “Most of my political energy will be spent working on that exact goal.”

Mr. Gonzalez said there had been some uncertainty after the assault on the Capitol over whether Republican leaders would continue to bow to Mr. Trump.

But the ouster of Representative Liz Cheney from her leadership post; the continued obeisance of Representative Kevin McCarthy, the House minority leader; and the recent decision to invite Mr. Trump to be the keynote speaker at a major House Republican fund-raiser were clarifying. At least in Washington, this is still Mr. Trump’s party.

“This is the direction that we’re going to go in for the next two years and potentially four, and it’s going to make Trump the center of fund-raising efforts and political outreach,” Mr. Gonzalez said. “That’s not something I’m going to be part of.”

His decision to leave rather than fight, however, ensures that the congressional wing of the party will become only more thoroughly Trumpified. And it will raise questions about whether other Trump critics in the House will follow him to the exits. At the top of that watch list: Ms. Cheney and Representative Adam Kinzinger of Illinois, who are both serving on the otherwise Democratic-dominated panel investigating the Capitol riot.

Asked how he could hope to cleanse the party of Mr. Trump if he himself was not willing to confront the former president in a proxy fight next year against Mr. Miller, Mr. Gonzalez insisted that there were still Republicans in office who would defend “the fundamentals of democracy.”

With more ardor, he argued that Mr. Trump has less of a following among grass-roots Republicans than the party’s leaders believe, particularly when it comes to whom the rank-and-file want to lead their 2024 ticket.

“Where I see a big gap is, most people that I speak to back home agree with the policies but they also want us to move on from the person” and “the sort of resentment politics that has taken over the party,” Mr. Gonzalez said.

Congressional maps are set to be redrawn this year, and it’s unclear what Mr. Gonzalez’s district, the 16th, will look like afterward. But he said he would probably not take sides in the primary to succeed him, which is now likely to include additional candidates.

He said he would remain in the House through the end of his term unless something changed with his family.

Mr. Gonzalez was emphatic that the threats were not why he was leaving — the commute was more trying, he said — but in a matter-of-fact fashion, he recounted people online saying things like, “We’re coming to your house.”

In accordance with the advice House officials gave to all members, Mr. Gonzalez had a security consultant walk through his home to ensure it was well protected.

“It’s a reflection of where our politics looked like it was headed post-Jan. 6,” he said.

Neither Mr. Trump nor any of his intermediaries have sought to push him out of the race, Mr. Gonzalez said.

Asked about Mr. Trump’s inevitable crowing over his exit from the primary, Mr. Gonzalez dismissed the former president.

“I haven’t cared what he says or thinks since Jan. 6, outside when he continues to lie about the election, which I have a problem with,” he said.

What clearly does bother him, though, are the Republicans who continue to abet Mr. Trump’s election falsehoods, acts of appeasement that he said were morally wrong and politically foolhardy after the party lost both chambers of Congress and the White House under the former president’s leadership.

“We’ve learned the wrong lesson as a party,” Mr. Gonzalez said, “but beyond that, and more importantly, it’s horribly irresponsible and destructive for the country.”