U.S. Rep. Tim Walz, a leading DFL candidate for governor, is proposing a Minnesota assault weapons ban, threatening to upend his support among gun owners as he seeks to reassure progressive voters that he hears them on an emotional and timely issue.

“I’ve spent my time since last week’s shooting listening closely to students, parents, law enforcement, teachers, sportsmen, and survivors of gun violence all across our state,” Walz said in a Facebook post Tuesday, referring to the mass shooting at a Florida high school. “I’ve heard their anger, grief, and frustration at the division and misunderstanding that has been keeping us from actually doing something.”

The assault weapons ban proposal is just the latest indication that Walz is distancing himself from his identity as a gun rights champion who won election in a Republican-leaning southern Minnesota district in 2006. He won regular backing from the National Rifle Association and frequently touted marksmanship skills developed in part during his 24-year military career.

On guns, Walz is balancing a heavy political plate in each hand. He must appease Twin Cities progressives who want gun control and view his NRA endorsements with disdain. But he is also trying to persuade many of those same progressives, who are desperate to win in 2018, that he’s the best candidate to appeal to voters in greater Minnesota — where the DFL has been shellacked in recent elections — because he speaks their language on issues like guns.

As recently as 2016, Guns and Ammo magazine called Walz one of the 20 best lawmakers on gun rights. He said in an interview Tuesday that his relationships with gun owners would allow him to bring them into the conversation.

“This is about bringing in responsible gun owners who understand something’s got to be done,” Walz said.

Bryan Strawser, chairman of the Minnesota Gun Owners Caucus, said Walz is mistaken: “Tim Walz’s relationship with gun owners was directly related to his strong advocacy for gun rights. He will soon learn how little of their support he has since he has forsaken them for political expediency.”

On the other side, Walz has faced repeated attacks from his competitors for the DFL nomination, who cite his past NRA support as evidence that he is untrustworthy on an issue of increasing concern to the party’s progressive base.

“It has been nearly impossible to even begin a serious and overdue discussion on how to make our communities safe and free from gun violence because of the stranglehold the NRA has on elected officials and our politics,” Rep. Erin Murphy, a St. Paul DFLer running for governor, said in a statement after last year’s Las Vegas mass shooting — a reference to Walz’s support from the gun rights group.

Walz donated his past NRA contributions to charity. While emphasizing in the interview that he’s been edging away from the NRA line for years by backing universal background checks and restrictions on people on the “no-fly list” from buying guns, he acknowledged that his overall position has changed significantly.

“The world’s changed. I’ve changed,” he said.

State Auditor Rebecca Otto, who came in second behind Walz in the recent DFL caucus straw poll, said Walz’s change of heart seems less than sincere.

“He had many opportunities to change, and the only thing that’s changed is that he’s running for governor, and it’s an issue,” Otto said. “He could have changed after Sandy Hook. He didn’t, and he continued to take money from the NRA,” said Otto, referring to the 2012 mass shooting at a Connecticut elementary school.

Otto put out her own gun control plan Tuesday, including universal background checks; banning “bump stocks,” which are the rapid-fire devices used in the Las Vegas massacre; and a ban on AR-15s and high-capacity magazines.

Murphy said she is introducing gun legislation this session, including many of the same ideas as Walz and Otto, plus gun owner orders of protection, which would allow a judge — after a hearing — to temporarily confiscate guns from those feared to be a danger to themselves or family.

Of Walz, Murphy said: “That the congressman is finding his voice in this is a good thing, but it’s taken him too damned long.”

Walz said being governor is different from being congressman from a rural district.

“I’m not just asking to be the congressman from the First Congressional District,” Walz said. “I’m looking at a broader state with broader issues, broader population densities, and I think as a legislator I’ve been proud to say if the facts dispute our ideology, change the ideology.”