LOUISVILLE, Ky. — Donald Trump slammed Hillary Clinton as “heartless” for backing restrictions on gun ownership that he said would leave Americans in high-crime areas unable to protect themselves.

He also challenged Clinton to follow his lead and release a list of potential Supreme Court nominees.

Trump’s remarks came at the National Rifle Association convention in Louisville, Ky. The gun rights organization endorsed the presumptive Republican nominee ahead of his remarks, despite Trump’s previous support for measures like an assault weapons ban that the NRA vigorously opposes.

Chris Cox, the NRA’s chief lobbyist, said that for those who preferred other candidates to Trump, “It’s time to get over it.”

The businessman has taken a far less restrictive stance on guns during the Republican presidential primary. His call for ending “gun-free zones” across the country was welcomed by the crowd.

Trump centered his remarks on Clinton, claiming she would seek to “abolish” the Second Amendment through the Supreme Court and release violent criminals if elected president.

He also called her “Heartless Hillary” — a new nickname from the branding expert for the likely Democratic nominee — for backing restrictions aimed at reducing gun deaths, saying her proposals would instead leave law-abiding citizens exposed to criminals.

“She’s putting the most vulnerable Americans in jeopardy,” Trump said. He added that women in particular would be at risk, a nod to what he has said will be a security-focused appeal to women in the general election. Trump heads into the fall campaign with stunningly high disapproval ratings with women. The supremely confident Trump appeared to acknowledge that weakness, saying that while his poll numbers with men are strong, “I like women more than men.”

Clinton has said she supports the Second Amendment but safety measures are needed to keep firearms out of the wrong hands and reduce the nation’s 33,000 annual gun deaths.

She has called for expanding background checks to sales at gun shows and online purchases, and for reinstating a ban on assault weapons.

Trump backed an assault weapons ban, as well as slightly longer waiting periods for gun purchases, in a 2000 book. He has since said such bans don’t work and has also called for making it easier for law-abiding citizens to carry guns for self-protection.

On Friday, he reiterated his call for ending “gun-free zones” and touted the list of potential Supreme Court nominees he released this week as a sign of his commitment to upholding the Second Amendment.

“I’d like to call for Hillary Clinton to put together a list also,” said Trump, predicting her potential justices would be a “day and night” difference with his. He also said he expects the next president to appoint between three and five justices to the high court.