Less than a week before calling for more gun control laws, President Trump invited boos at a massive Ohio campaign rally, warning 17,000 supporters that if Democrats reclaim power, “there is no Second Amendment.”

Within 72 hours of the rally, gunmen randomly murdered nearly three dozen people in nearby Dayton and in El Paso, Texas. And despite the campaign line, Trump called for new restrictions, outraging gun rights hard-liners.

Trump told reporters that he would “certainly” bring up a semiautomatic gun ban, and pushed lawmakers to expand mandatory background checks and to allow temporary gun confiscation.

“I'll be convincing some people to do things that they don’t want to do, and that means people in Congress,” Trump said, calling for “great legislation after all of these years."

Michael Hammond, legislative counsel of Gun Owners of America, which claims 2 million members and supporters, said Trump risks losing both conservative and traditionally Democratic Midwestern voters.

“I am no longer committed to voting for Donald Trump,” said Hammond, who spends most of his time in New Hampshire. “I think he’s about to make his ‘read my lips’ mistake. He thinks he can do anything on the Second Amendment and gun owners will love him.”

Hammond’s group positions itself as a bolder alternative to the larger National Rifle Association, which has about 5 million members. And he said he’s concerned that Trump could pass historic gun control legislation that Republicans successfully blocked under President Barack Obama.

“You don’t have to lose every member of the NRA to be a one-term president. You have to lose about as many as he is on the verge of losing,” Hammond said. “The bitter clingers are sitting there in the western tier of Pennsylvania, Macomb County, Michigan and in north Wisconsin.”

Trump defeated Hillary Clinton by fewer than 80,000 votes across the three states, where many Democrats voted for Trump after he campaigned on economic issues.

Although polls indicate broad support, gun activists say requiring federal background checks for private sales could turn people into felons for innocent transfers. Previously failed legislation drafted by Sen. Patrick Toomey of Pennsylvania, exempts family transfers.

So-called “red flag” laws pushed by Trump, meanwhile, allow courts to authorize police to take guns from people considered to be safety risks. Gun activists say they can be manipulated by angry exes and relatives, and that enforcing laws against threats and other crimes could achieve similar ends.

Legislation being prepared by Sen. Lindsey Graham of South Carolina, would incentivize state "red flag" laws.

Brandon Combs, president of the Firearms Policy Coalition, said "this is the same president who said take the guns first, due process later," after the Parkland, Florida, shooting, and who ordered a ban on bump stocks in response to the 2017 murder of 58 in Las Vegas.

“There’s going to be a lot of people who see these types of anti-Second Amendment policies as a reason to stay home,” Combs said. “With President Trump, what we're going to get is a New York liberal who calls himself a Republican.”

“We never trusted him,” Combs added. “We certainly don’t trust people who don’t have an understanding of how the Constitution works. [Trump] has gone out of his way on guns and firearms policy to show how little he understands how the Constitution works, how our culture works.”

In a statement, the NRA defended Trump.

“Donald Trump is the most pro-Second Amendment president in recent American history. From nominating Neil Gorsuch and Brett Kavanaugh to the U.S. Supreme Court, to removing the United States from the United Nations gun ban treaty, President Trump has stood strong for the rights of law-abiding gun owners," the group said.

Josh Blackman, a South Texas College of Law professor, said that although expanded background checks “could make a lot of people criminals,” he doubts Trump’s cumulative gun record will meaningfully sway voters.

Robert Spitzer, a professor at SUNY Cortland and author of five books on gun policy, said while “some of the extremist gun people may be unhappy with Trump ... where else are they going to go?”

At this point, Spitzer said, "I do not believe they represent anything like a real movement of gun people to either stay home or desert Trump."