Former congresswoman Gabrielle Giffords and her husband Captain Mark Kelly appear at Atomic Coffee in Fargo, N.D., to promote stricter gun-control measures during the Americans for Responsible Solutions tour on July 3. (Nikki Kahn/The Washington Post)

In Colorado, a state scarred by two mass shootings, Democrats passed some of the nation’s toughest gun legislation this year. Gun rights supporters responded by recalling two state senators who had championed the bills.

Now gun-control advocates are plotting their revenge. Inside a hotel conference room here this week, 60 activists spent a day strategizing to defend the remaining legislators who voted for the measures and protect them from repeal efforts. They also vowed to take a page from their opponents’ playbook by possibly mounting campaigns to recall Republicans who opposed the new restrictions.

Gun-control activists have largely given up on Congress, which did not pass background-check legislation after the school massacre in Newtown, Conn., last December that killed 20 children and six adults. The groups are shifting their resources to a handful of states such as Colorado, where they have hired political operatives to try to build permanent gun-control movements.

The effort, however, is certain to run into heavy resistance from gun rights groups such as the National Rifle Association, which has focused for years on building relationships with state legislators, contributing to their campaigns and hiring lobbyists to pressure them to loosen existing laws or block legislation.

Groups run by New York Mayor Michael R. Bloomberg (I), former congresswoman Gabrielle Giffords (D-Ariz.) and other gun-control advocates intend to spend more than $25 million in 2014, most of it in the states, said officials with knowledge of the plans, which have not been previously reported. Their strategy is to pressure state legislatures and pursue ballot initiatives for stricter gun laws, as well as to defend or attack politicians in next fall’s campaigns based on their gun votes, the officials said.

Matt Bennett of Third Way, who has worked with the Newtown families for the past year, tells On Background's Pamela Kirkland gun control legislation efforts can take years to enact. (Natalie Jennings/(On Background))

A consensus has emerged among activists that pushing for federal background checks is a lost cause for now.

“It was a confusing time right after Newtown and the horizons of the possible grew tremendously,” said Arkadi Gerney, a senior fellow at the Center for American Progress who convened the Denver strategy summit. But, he added, “there’s no shortcut, no silver bullet.”

Gerney said the groups are “not giving up federally, but recognizing that in order to move something federally you’ve got to go to the contested territory, whether it’s congressional districts or states, and build a stronger movement there.”

The Senate this spring did not pass a package of gun laws, including expanding federal background checks for firearm purchases, which polling showed was overwhelmingly popular. The NRA pressured lawmakers to block the bill. In the first half of 2013, the NRA and other gun rights groups outspent gun-control organizations on federal lobbying, $12.2 million to $1.6 million, according to the nonpartisan Sunlight Foundation.

As a result, gun-control advocates have calculated that state lawmakers might be more open to considering such measures as expanding background checks, banning assault weapons and limiting the size of ammunition magazines.

Pia Carusone, executive director of Americans for Responsible Solutions, the group Giffords and husband Mark Kelly founded, said, “I think state legislators aren’t as ingratiated into the hardened political system as members of Congress and the Senate are. It’s not that they’re naïve, but they’re more confident that they can tell their side of the story without the fear of the special interests.”

In addition to Colorado, the Center for American Progress is convening strategy summits with representatives of the major gun-control groups in Georgia, Minnesota, Pennsylvania, Virginia, Washington state and Wisconsin. The sessions include tutorials for gun violence victims and other local activists on how to tell emotional stories to lawmakers and in the news media.

Dudley Brown, a leader of the National Association for Gun Rights, an umbrella organization of state-level groups, scoffed at the notion that gun-control advocates would find success in the states. Brown helped organize the recall campaigns in his home state of Colorado, and warned that his group will work to defeat “gun grabber” lawmakers in other states as well.

“We’ll go after legislators who went wrong on the issue, even Republicans,” he said. “When they get weak-kneed, we’ll go after them.”

An NRA spokesman declined to detail the group’s state strategies for 2014, although data suggest that it was successful in 2013. In the year since the shootings at Sandy Hook Elementary School in Newtown, 1,500 state gun bills were introduced. Of the 109 that became law, nearly two-thirds loosened gun restrictions, according to a New York Times analysis .

In Washington state, for example, legislation to expand background checks did not pass the Democratic-controlled House, despite lobbying from Giffords.

Activists with the Washington Alliance for Gun Responsibility hope to take the issue to voters, collecting signatures from about 325,000 state voters to force background checks on the ballot in the 2014 elections.

“When you’re playing in these narrow legislative districts and the narrow hallways of the legislatures, you’re on your opponent’s turf,” said Zach Silk, who is managing the ballot initiative campaign. “So we decided to take it directly to the people.”

Gun-control advocates in other states where bills narrowly failed or were vetoed also are vowing to try again, including Nevada and Oregon.

“The public is better educated and knows solutions are available and supports them, and a movement has begun to build for change that we know will come,” said Mark Glaze, executive director of Mayors Against Illegal Guns. “But change takes time.”

The victories claimed by gun-control advocates over the past year have been small. In Virginia, they note that Gov.-elect Terry McAuliffe (D) campaigned on toughening firearms restrictions, saying in one debate, “I don’t care what grade I got from the NRA.”

They also see opportunity in Minnesota, Pennsylvania and Wisconsin, where citizens have been organizing chapters of grass-roots volunteers to push for tougher laws.

“If you’re a suburban mom outside of Philadelphia who’s angry about this issue, just because it wasn’t on the floor of the Senate doesn’t mean you woke up and stopped caring about it,” said Jon Carson, executive director of Organizing for Action, a nonprofit group formed from President Obama’s reelection campaign.

Here in Colorado, Brown, the gun rights group leader, said he will use the new firearm laws “as a sledgehammer” to “destroy” Gov. John Hickenlooper (D) and Democratic state legislators who are up for reelection in 2014. “I’m going to wade through their China shop,” he said.

Gun-control supporters here said they are prepared to fight back. At the Denver strategy summit, pollster Kevin Ingham presented results and video from focus groups on the two state senator recall elections. His conclusion: It wasn’t the gun laws that led to their defeat, but a confluence of factors, including a negative perception that they had “gone Denver” and were being controlled by party bosses.

“You can actually win on this issue,” Ingham said, noting that women in particular tend to support the laws.

State House Speaker Mark Ferrandino (D) said, “We’re going to defend the laws we passed and we’ll have the evidence to show that it’s working.”

Since Colorado’s law took effect in July, background checks have stopped 72 criminals or domestic violence abusers from buying guns, according to newly released state data.

State Senate President Morgan Carroll (D), whose district includes the Aurora movie theater where 12 people were killed and 70 others injured in a shooting last year, took over after then-Senate President John Morse (D) was recalled. She said she has an answer for critics of the gun laws.

“It’s like, ‘Really? Really? You really don’t think there should be a process to keep guns out of the hands of criminals?’ ” Carroll said. “That’s not a mainstream view in this state.”