CLARENCE, N.Y. (AP) — After back-to-back mass shootings last spring, including one that killed 10 people at a supermarket not far from his suburban Buffalo home, Republican U.S. Rep. Chris Jacobs made a decision.

If an assault weapons ban came to the House floor, he would support it, he told voters in his conservative congressional district.

“I could have said nothing,” said Jacobs. Silence would have allowed him to cruise through the Republican primary. But after 31 deaths in 10 days, including the slaying of 19 children at a school in Uvalde, Texas, he felt he had an obligation to take a public stance.

“Having two young children, it just really — you have a different perspective when, you know, thinking about going home to your kids when those 19 children perished,” Jacobs said.

A week later came another decision. With Republicans withdrawing their support for him in droves, Jacobs announced he would not seek reelection.

The expiration of his career is another sign of the polarization that is ever-growing in a Congress where, as Jacobs said, “If you stray from a party position, you are annihilated.”

“There’s a lot of single-issue voters in the Republican Party on this issue, and on the other side, abortion,” he said in an interview with The Associated Press.

“The idea of big tents for parties, I think, is very important. And right now it’s very strident both ways, and I just don’t think that’s good,” he said. “The polarized nature is why you see a lot of frustrated members of Congress and not enough is getting done.”

But if there is regret for the decision that abruptly halted his political career, it doesn’t show. On his way out of Congress, the Republican serving his first full term has doubled down on his support for the regulation of certain high-powered firearms, proposing a licensing regimen for people who want to buy them.

“Ninety-nine percent of people are very responsible gun owners. Unfortunately, saying it’s only 1% (who are not) gives no solace to someone who lost somebody senselessly in Buffalo or in one of these mass shootings,” Jacobs said.

His Federal Assault Weapons Licensing Act would require people to take a safety course, pass an FBI background check and submit fingerprints before buying a “semi-automatic assault weapon.” There are exemptions, including for current owners, active duty military and law enforcement officers.

The steps would be similar to those required for the thousands of pistol permits Jacobs issued during five years as Erie County clerk, a process he considers a reasonable balance between Second Amendment protections and responsible ownership.

Many of Jacobs’ former supporters see his position as a betrayal.

“It’s just not really tolerable,” said the state’s Conservative Party chair, Gerard Kassar.

“In terms of single issues, the Second Amendment in parts of upstate New York … is a very, very significant single issue and represents more than just the issue of guns,” Kassar said. “It represents the issue of freedom, represents an issue of constitutionalists. It represents the position of libertarians.”

Donald Trump Jr. tweeted that Jacobs had “caved to the gun-grabbers.”

Jacobs’ reputation as a moderate has, until now, worked to his advantage. He was the first Republican to be elected Erie County Clerk in 40 years and gained acceptance on the school board in the heavily Democratic county seat of Buffalo.

He was serving in the state Senate when, with the endorsement of President Donald Trump, he won a special election to Congress in June 2020.

In Congress, Jacobs was endorsed by the National Rifle Association, voted against impeaching Trump and has strongly advocated for completion of the wall begun by the former president along the southern border.

But his break with the party on guns began when an 18-year-old shooter killed 10 Black people and wounded three victims at a Tops Friendly Market near where his real estate development business is based.

“It was profound to all of us,” said Jacobs, a member of a prominent Buffalo family. His uncle is Jeremy Jacobs, the billionaire owner of the Boston Bruins and chair of concessions giant Delaware North.

Two weeks later, another 18-year-old with a similar weapon opened fire at the elementary school in Uvalde, killing 19 students and two teachers. This time, Jacobs’ thoughts turned to his own children, one 3 and the other less than a year old.

When the House in July voted to ban certain semi-automatic guns for the first time since 2004, he was one of two Republicans to support the proposal, which had little chance in the U.S. Senate.

If Jacobs had decided to run for reelection, he would have been campaigning in a newly drawn district that was even more conservative than the one he now represents in the suburbs and rural areas around Buffalo.

The new territory would have included six new mostly rural counties along the Pennsylvania border in which he is largely unknown.

“Clearly if I ran — and I thought I could have pulled it off — but I thought the NRA, it would have been outside money galore and I just didn’t think that was good for the district or the party,” Jacobs said, “and I just decided it was not right to do.”

The state’s Republican committee chair, Nick Langworthy, ultimately won the primary in the new district and will be the prohibitive favorite against Democrat Max Della Pia in November. Langworthy stepped in after saying he was caught by surprise by Jacobs’ support for a ban on semi-automatic firearms.

“I think everybody was caught very flat-footed by his adopting the Democrat position on gun control,” he said at the time.

If elected, Langworthy “would not support an assault weapons ban or any other legislation that limits the constitutional rights of law-abiding Americans and has been proven ineffective,” his campaign spokesperson, Chris Grant, said in a statement Tuesday to the AP.

Andrea Nikischer, who co-founded a progressive group in Jacobs’ current district, has long criticized the Republican over his politics and pro-Trump votes. Nevertheless, she was disappointed by his decision to leave office after shifting his stance on guns.

“I’m sorry he didn’t run,” she said. “I think it would have been a very meaningful discourse, and he could have pushed his party in a more positive direction. The power of incumbency is strong, and I wish he had used that power to push this discussion in his own party further.”

Jacobs has not yet found support for his assault weapons licensing proposal and doesn’t expect to see it emerge with the election just weeks away.

But he said he’s hopeful more support might emerge after November.

“I’m going to put this forward,” he said, “and I hope somebody grabs it.”