The Democratic senator leading his party’s push for stronger gun laws said on Sunday he believed measures passed in Florida following the 2018 high school shooting in Parkland could attract Republican support and provide a workable template for action in Congress.

Chris Murphy of Connecticut, speaking on CNN’s State of the Union, said he was optimistic that recent mass shootings in Buffalo, New York, and Uvalde, Texas, could finally prompt enough bipartisan support for legislation that has previously proven elusive.

But he also warned of “significant” consequences if lawmakers failed to act.

“I’m more confident than ever that we’re gonna get there,” Murphy said. “But I’m also more anxious about failure this time around.

“In Connecticut last week I’ve never seen the look in parents’ faces that I did. It was just a deep, deep fear for our children. And also a fear that things in our country are so fundamentally broken that you can’t put politics aside to guarantee the one thing that matters most to adults: the safety of their children.”

Murphy added: “The possibility of success is better than ever before. But I think the consequences of failure for our entire democracy are more significant than ever.”

Florida, a Republican-controlled state, acted swiftly after the murders of 17 students and staff at Marjory Stoneman Douglas high school in February 2018, passing red flag laws and raising the age requirement for buying, but not owning, firearms from 18 to 21, among other steps. The Parkland gunman was 19.

In his address to the nation last week, Joe Biden called for a federal ban on semi-automatic weapons, and raising the age requirement if that couldn’t be done.

Murphy acknowledged the Florida actions and said “there is interest in taking a look at that age range, 18 to 21” during bipartisan discussions about possible legislation, led on the Republican side by Texas senator John Cornyn.

“Right now we’re trying to discover what can get to 60 votes [in the Senate],” Murphy said.

“But I think the template for Florida is the right one, which is some significant amount of investment in school safety and some modest but impactful changes in gun laws. That’s the kind of package we’re putting together right now.

“As Senator Cornyn said, there is interest in looking at that age range … and doing what is necessary to make sure that we aren’t giving weapons to anybody that has, during their younger years, a mental health history, a juvenile record.

“Often those juvenile records aren’t accessible when they walk into the store buying as an adult. So we’re having a conversation about that specific population, 18 to 21 and how to make sure that only the right people, law abiding citizens, are getting their hands on weapons.”

With a handful of exceptions, Republican politicians have remained resolutely opposed to any kind of gun reforms, despite polls showing overwhelming public support for “common sense” measures including red flag laws and expanded background checks.

In an appearance on Fox News Sunday, Republican House minority whip Steve Scalise, who was shot by a gunman in a 2017 attack during practice for the congressional baseball game, attempted to paint soaring gun crime in the US as solely a mental health issue.

“We are not focusing on the root cause of the problem,” Scalise said.

“The immediate visceral reaction of Democrats in Washington is to go after the rights of gun owners in America. We need to be focused more on stopping things before they happen.”

Murphy said he hoped the negotiations, which have been ongoing during the Senate’s Memorial Day recess, will lead to a vote that could finally pass the chamber.

“This time we have far more Republicans,” he said. “We don’t need to have competing proposals on the Senate floor. We need one proposal that can get 60 to 70 votes from both parties.”

Democratic senator Pat Toomey of Pennsylvania said on CBS’ Face the Nation he hoped any proposal would include an expansion of background checks, at least for commercial sales of guns.

“We all agree violent criminals and deranged, dangerously mentally ill people shouldn’t have firearms,” he said, noting that lawmakers “not engaged on this in the past” have been involved now in negotiations.