Accused Aurora movie theater shooter James E. Holmes appears in Arapahoe County District Court in Centennial, Colo., on July 23, 2012. (RJ Sangosti/AP)

There could hardly be a starker divide on guns than in Colorado.

Metropolitan Denver, home to hipster cafes and pot dispensaries, has been hit by two of the most horrific mass shootings in recent years, Columbine and ­Aurora. Leave the city and you get to areas where the nearest police officer could be a 20-minute drive and owning a weapon for self- defense becomes more than a talking point.

The state legislature is now caught up in a bitter struggle over whether to tighten its gun laws. While advocates acknowledge the proposals are modest, if enacted they would represent the first gun-control measures adopted in the American interior since the Newtown massacre in December.

It’s been more than a decade since Colorado tightened its gun laws. And the outcome of the current battle remains much in doubt. Seven gun-control bills are scheduled for a vote in the state Senate on Friday. Four of those measures already passed the state House last month by a narrow margin and the Senate vote is expected to be even closer.

The ultimate fate of the meas­ures in this political swing state could say much about whether the Connecticut killings have fundamentally reshaped the national debate over firearms and how gun-control efforts will fare beyond the state’s borders.

The Washington Post’s Ed O’Keefe shows us some of the guns targeted by legislation that would outlaw certain rifles, pistols and high-capacity magazines. (The Washington Post)

Colorado’s legislation mirrors much of what has been proposed at the federal level in the U.S. Senate, including universal background checks and limits on large ammunition clips, and many of the arguments made by both sides are similar. But here, they often have more of an edge.

“We spent the last ten years playing defense,” said Tom Mauser, an advocate for tighter gun laws since his son was killed in the shootings at Columbine High School in 1999. “It was a game changer in Aurora, and then Connecticut just sealed it.”

In recent months, Mauser has been joined by family members of the Aurora shooting victims, such as Dave Hoover, who has been meeting with lawmakers in the months since his nephew was shot dead during the killings at the movie theater last summer.

Advocates of tougher laws have been surprised by the groundswell of support. In January, more than 200 people turned out at a Denver church to join a lobbying push, more than double what organizers had expected.

“Sandy Hook pushed me over the edge,” said Christine Lund­gren, 48, a real estate agent from Denver who came out to a similar church meeting late last month and, over coffee and cookies, was writing letters to her state legislators. “I’m tired of being an armchair person who’s waiting for common sense to take hold.”

Yet resistance to the proposals remains broad and deeply felt.

The most vocal opposition comes from the Rocky Mountain Gun Owners, whose founder, Dudley Brown, chastises the National Rifle Association (NRA) as too moderate because “they’re prone to cutting deals.” Membership in his group has grown by 50 percent since November, Dudley said, and its e-mail list now numbers 60,000 people. The group’s stickers featuring a handgun have become a common sight around the state.

In Denver’s western suburbs last weekend, self-described “gunnies” crowded into a town hall meeting with their state senator. Muscular men in mirrored sunglasses and frayed baseball caps packed the rows of chairs.

One after another, speakers rose to cite riots and terrorism as threats to their safety. To applause, Kelley Sands, a 50-year-old resident of Wheat Ridge, urged that the Second Amendment isn’t just about a right to hunting or sport shooting.

“What it’s about is having military firepower to repel foreign invaders,” he said. “It’s about maintaining a check on government when it gets out of control and tyrannical, like it is right now.”

A national debate

Since the Newtown shooting, state legislators across the country have been introducing gun-control bills similar to federal proposals aimed at requiring universal background checks, prohibiting assault weapons and limiting or banning high-capacity magazines.

As of last month, there were at least 344 new bills across the country to strengthen gun control laws, according to the San Francisco-based Law Center to Prevent Gun Violence, which tracks gun legislation nationwide.

“It reflects a real sea change in the public’s opinion about what legislatures across the country ought to be focusing on,” said Arkadi Gerney, a senior fellow at the Center for American Progress.

New York has passed stronger gun control laws, and legislation is making its way through statehouses in both California and Maryland. Connecticut Gov. Dan Malloy (D) last week announced proposals for universal and comprehensive background checks for gun buyers, a ban on high-capacity magazines and steps to strengthen Connecticut’s assault weapons ban.

“But there are also bills in states like New Mexico and Minnesota, places that have historically been challenging territory for gun legislation,” Gerney said.

At the same time, there are widespread efforts to roll back gun restrictions. By last count, 346 bills have been introduced in state legislatures that would weaken gun control laws.

The state House in Wyoming, for instance, overwhelmingly passed a measure that would prohibit enforcement of new federal gun-control laws. In Missouri, a dozen bills have already been introduced to expand gun rights, including a plan that would allow teachers to carry guns in their classrooms, and a Missouri lawmaker offered a bill that would make it a felony for his fellow legislators to introduce legislation restricting gun rights.

Over the past decade, efforts to restrict guns had also been losing ground in the frontier state of Colorado. In 2003, the legislature made it legal to carry a concealed weapon anywhere in the state. The state Supreme Court later found that the law applied to the public universities as well.

But Democratic gains in Colorado, along with the fallout from Newtown, has shifted the momentum. After years of building a powerful political organization and spending millions of dollars in campaign money, Democrats won control of the state House last year, completing their hold on power.

That political success translated into the House passage last month of four gun-control bills solely on Democratic votes. The measures would require background checks for all private sales, limit ammunition magazines to 15 rounds and ban concealed weapons on college campuses.

Voters weigh in

As in Congress and across many other states, universal background checks have the most support. Eighty percent of Colorado residents support universal background checks, according to two recent polls that found identical results.

Restrictions on high-capacity magazines face a less certain future with some Senate Democrats saying they oppose the 15-round limit.

Three new bills are originating in the Senate, including measures targeting guns in domestic violence cases and eliminating online training for firearms permits. Senate President John Morse has proposed a bill that would make gun manufacturers and dealers, among others, liable for deaths from weapons they produce and sell.

Both sides in this debate are flush with cash. New York’s billionaire mayor, Michael R. Bloomberg, is backing the campaign for gun restrictions, and millions of gun enthusiasts and manufacturers contributing to the NRA. Both camps have run advertising in newspapers and on the radio in Colorado this winter.

Magpul Industries, a local manu­facturer of high-capacity ammunition magazines, has also been taking out newspaper ads warning it will move out of state if the 15-round limit becomes law. At the company’s request, gun-control advocates said they agreed to allow the continued manufacture of large magazines, though not the sale, and raised the proposed limit from 10 rounds to 15.

Legislators say they’ve been besieged with phone calls and e-mail over the legislation.

State Sen. Cheri Jahn, a Democrat from Denver’s Wheat Ridge suburb, said she received 600 ­e-mails in one weekend about guns, mostly opposing the restrictions.

A small-business owner and a single mother of three, Jahn grew up around guns in northeast Colorado, where her father was a hunter. Democrats recruited her to run for the legislature a dozen years ago. Following a redrawing of boundaries in 2011, she now represents a more conservative district, and she says that fits her own philosophy of personal responsibility, which she described as “put your big girl panties on and deal with it.”

Her fellow Democrats are looking for her support on gun control, but Jahn is skeptical.

She backs universal background checks but said she will vote Friday against limiting the size of magazines. She doubts such a restriction would be enforceable because existing magazines would stay in circulation and residents would still be able to buy new ones outside Colorado.

Moreover, she offered, the main problem contributing to mass shootings is poor mental health, and the legislature shouldn’t pass new laws just to send a message following a massacre.

“This one has taken more of my sleep than many,” Jahn says. “Either way I go, I’ll be in trouble.”

Sari Horwitz contributed to this article.