DENVER (AP) -- Colorado's most sweeping gun control package in memory advanced Friday, with expanded background checks and other limits winning approval in the Senate despite marathon attempts by Republicans and gun-rights activists to stop the bills.

Republicans weren't giving up attempts to derail parts of the gun package, stretching debate past 12 hours on a snowy night while furiously tweeting supporters to try to persuade Democrats to change course. The debate appeared headed past midnight.

Republicans spent more than five hours trying to derail one of their most hated proposals, a limit on ammunition magazines.

The gun control proposals were closely watched in a state that balances a history of heartbreaking shootings with a Western heritage where gun ownership is treasured by many.

Democrats shepherded through expanded background checks on private gun purchases and a new ban on gun ownership by people facing domestic-violence accusations. The measures passed after hours of debate as Republicans tried in vain to argue the gun proposals change Colorado's character and violate the Western ideal of self-reliance.

"What do we hate today? Freedom? Liberty?" said Republican Sen. Ted Harvey of Highlands Ranch. "The right of self-protection?"

The Colorado debate is being watched nationally as a bellwether of how far politically moderate states are willing to go with new gun laws in the wake of mass shootings in a suburban Denver movie theater and a Connecticut elementary school. It's also playing out in a state where one of the nation's most high-profile school massacres — the 1999 Columbine High School shootings — took place.

Already the White House has weighed in, with Vice President Joe Biden phoning four lawmakers while on a recent ski vacation here to nudge the Democrats during their first major gun debate last month.

Lawmakers pushing for the stricter measures face powerful opposition from gun-rights advocates. They flooded the state Capitol by the thousands earlier this week, waving "Don't Tread On Me" flags and blaring car horns as they circled the block while bills were being considered in committees. Some Democrats have reported getting threats.

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The stakes got higher with Friday's marathon Senate debate, which included seven Democratic gun control measures.

Democrats have argued the country's mass shootings painfully illustrate the need for tighter gun controls. They insist the measures don't compromise Colorado's gun-loving heritage.

"I'm a gun owner, and I have been since I was 12 years old," said Democratic Sen. Mike Johnston of Denver. "What is before us is not a constitutional question but a policy question."

Democrats hold a 20-15 advantage in Senate, meaning they have a narrow margin to pass the bills. But parts of their package were in question Friday.

One of the measures — to end Colorado's unusual practice of allowing concealed weapons on public college campuses — was in doubt, as was a set of liability standards for sellers and owners of assault weapons used in crimes.

Lobbying has been intense on Colorado's gun bills, and the pressure grew Friday. A suburban gun accessory maker that has threatened to leave the state if the magazine limit passes sent company executives to lobby wavering Democrats on that measure.

Some Democrats have reported getting threatening emails and phone calls. As senators debated, a man accused of threatening one of the Democrats appeared in court to answer criminal charges. In an appearance just down the street from the Capitol, Franklin Sain's lawyer told a judge Friday that Sain's emails and calls to state Rep. Rhonda Fields were constitutionally protected political speech.

Back in the Senate, lawmakers slogged through the seven firearms bills while deeper philosophical barbs about gun rights peppered the debate.

"This is a day of dysfunctionalism," griped Republican Sen. Steve King of Grand Junction.

Democrats frequently cited the Connecticut school shooting and the Aurora theater shooting as they argued the limits are needed.

Arguing for the magazine ammunition limits, Democratic Sen. Mary Hodge said the change to Colorado's heritage and the potential inconveniences on gun owners paled in comparison to the pain of gun violence.

"This bill is merely an attempt to reduce the slaughter," Hodge said.

Democratic Gov. John Hickenlooper has said he would sign into law a magazine limit and a background-check expansion, but 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.

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Ivan Moreno can be reached at http://www.twitter.com/IvanJourno and Kristen Wyatt at http://www.twitter.com/APkristenwyatt