DENVER (AP) — A bill to ban the sale and transfer of semi-automatic firearms was nixed in Colorado’s Democratic-controlled Legislature on Tuesday as lawmakers pressed forward with a slew of other gun control bills on the 25th anniversary year of the Columbine High School massacre.

The western state has a deep history with firearms that is pockmarked by some of the most high-profile mass shootings nationwide. Both factors loom large over gun control debates in the Legislature, complicating attempts at such bans that nine other Democratic-controlled states have in place, including California and New York.

The Colorado House passed the ban in a historic first, after roughly the same proposal was swiftly nixed last year. But some Senate Democrats are wary of the efficacy and breadth of the ban, which prohibits the sale, transfer and manufacture of semiautomatic firearms.

Colorado’s blue shift is evident in part by a number of successful gun control measures passed last year, including raising the buying age for a gun from 18 to 21. Some half-dozen proposals are nearing passage this year, including a bill to put a measure on the November 2024 ballot to tax sales of guns and ammunition.

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The state’s purple roots have frustrated attempts at a broader ban.

In the face of Senate Democrats’ opposition, one of the bill’s sponsors asked that the legislation be put to rest at a brief and sparsely attended committee hearing Tuesday.

“After thoughtful conversations with my Senate colleagues, I decided that more conversations need to take place outside of the pressure cooker of the Capitol,” sponsor Democratic state Sen. Julie Gonzales said.

Gonzales said she’ll continue discussions with gun violence victims, responsible gun owners and advocates “committed to doing the work necessary to save lives — and an assault weapons ban will do just that.”

On that committee sat Democratic state Sen. Tom Sullivan, who would have been a “no” vote, along with Republican lawmakers who have decried the bill as an encroachment on Second Amendment rights.

Sullivan’s son, Alex, was one of 12 killed in the 2012 Aurora theater shooting at a midnight screening of “The Dark Knight Rises.” The tragedy catapulted Sullivan into activism around gun control and then public office, where he has spearheaded many bills on the issue.

Sullivan said the weapons that the bill seeks to curtail are involved in only a small fraction of gun deaths and injuries. Those firearms include a long list of semi-automatic rifles, along with some pistols and shotguns, with certain characteristics, such as a threaded barrel or detachable stock.

Their prohibition wouldn’t make much of a dent in gun violence, Sullivan argued, and the proposal takes up immense political oxygen in the state capitol — energizing the opposition and detracting from more effective and less controversial gun control measures.

“The narrative is all wrong,” Sullivan said. “That’s what they want you to believe, that it’s assault weapons and schools. It’s not. ... It’s suicides and it’s domestic violence.”

The proposal is expected to be revived next year.

Meanwhile, other bills nearing the governor’s desk include a proposal to give Colorado’s Bureau of Investigations more power to investigate gun sales that are already illegal. Another would require more rigorous safety training for someone seeking a concealed carry permit. And one would require firearm dealers to be permitted by the state, not just the federal government, giving regulators greater power to enforce state law.