New restrictions on guns await a pivotal vote in battleground Colorado, where a single vote in the state Senate on Friday could determine whether some of the measures pass or fail.
The state Legislature was braced for hundreds of visitors and protesters as the Democratic Senate planned a marathon debate over seven gun measures.
Democrats have sponsored all the bills and hold a 20-15 advantage in the chamber, but the defections of at least two Democrats on some pieces have both sides braced for a drawn-out battle.
Among the most controversial gun controls pending Friday were a proposal to limit ammunition magazines to 15 rounds and a bill to end Colorado's unusual practice of allowing concealed weapons on public college campuses. Democratic Sens. Lois Tochtrop and Cheri Jahn, both from the Denver suburbs, have said they'll join the GOP against those measures. That leaves Democrats a razor-thin one-vote margin.
Both parties in the gun debate were talking confident as the votes neared.
"The world changed largely in Colorado in July with the Aurora theater shooting," Senate President John Morse said Thursday. "But when you've got 20 6- and 7-year-old kindergarteners that are massacred on December 14, I mean that just seared the consciousness of this generation. And I think you're seeing huge changes in the way people view gun violence and the way that we ought to be approaching it."
Republicans insist most Coloradans don't support the gun bills. Thousands of people filed into the Capitol on Monday, when Senate committees started work on the package of bills. Most of them opposed the measures, which also include expanded background checks for private gun purchases and new fees for people seeking background checks. Dozens stood outside waving "Don't Tread On Me" flags, while cars blaring their horns in protest of the gun control circled the Capitol for hours.
Ruling Democrats have already rejected several GOP gun proposals to expand gun rights. The failed Republican gun ideas included allowing school boards to permit employees to carry concealed weapons. Another measure would have required private businesses to provide armed security if they banned concealed weapons.
Morse said most of the public supports the Democrats ideas.
"He's not listening if that's the only thing he's hearing," said Republican Rep. Mark Waller, the GOP leader in the House.
Democrats have already passed some gun legislation through the House, including the background checks and the campus gun ban. Vice President Joe Biden, who was in Colorado at the time on a ski vacation, phoned at least four House lawmakers to ask about the gun package. Colorado is a politically moderate state being watched closely in the national gun-control debate.
Waller said lawmakers will ultimately know the truth about the level of opposition with the next election.
"I believe that in large part the voters will decide that in 2014, won't they?" he said.
Democratic Sen. Leader Morgan Carroll, who represents the district where the theater shooting happened, said Democrats are doing the right thing.
"If we failed to act, even before Newtown for my district, if we failed to act, we would be falling down on the job and it would be because of lack of courage. And I will be honest, it is taking some," she said.
Sen. Greg Brophy, who represents a rural district on the eastern plains, said Democrats have already damaged party's image to Coloradoans who support gun rights.
"I think the die is cast. I don't think there's anything they can do to salvage this tremendous black eye. The people who care about this, care deeply about it," he said.
Democratic Gov. John Hickenlooper has said he'd sign a magazine limit and a background-check expansion into law. But the governor said Thursday he hasn't made up his mind on the rest of the measures.
Talking to a group of high-school journalists Thursday, Hickenlooper said he's keeping his options open.
"I'm not in any way an anti-gun person," the governor said.