NEWTOWN, Conn. — Having already lost her 6-year-old son, Nicole Hockley insists she won’t lose the fight to reduce gun violence — no matter how long it takes.

She is among a group of “accidental activist” parents brought together one year ago by almost unthinkable grief after the Newtown school massacre. The shootings were so horrific that many predicted they would force Congress to approve long-stalled legislation to tighten the nation’s gun laws.

They did not.

A divided Congress denied President Barack Obama’s calls for changes. The national gun lobby, led by the National Rifle Association, is arguably stronger than ever. And surveys suggest that support for new gun laws is slipping as the Newtown memory fades.

A new Associated Press-GfK poll finds that that 52 percent of Americans favor stricter gun laws, while 31 percent want them left as they are and 15 percent say they should be loosened. But the strength of the support for tighter controls has dropped since January, when 58 percent said gun laws should be tightened and just 5 percent felt they were too strong.

After a year of personal suffering and political frustration, Hockley and other Newtown parents are fighting to stay optimistic as their effort builds a national operation backed by an alliance of well-funded organizations working to pressure Congress ahead of next fall’s elections. The groups are sending dozens of paid staff into key states, enlisting thousands of volunteer activists and preparing to spend tens of millions of dollars against politicians who stand in the way of their goals.

It may well take time, they say, to counter the influence of the NRA on Capitol Hill.

“I know it’s not a matter of if it happens. It’s a matter of when. This absolutely keeps me going,” says Hockley, who joined a handful of Newtown parents in a private White House meeting with Vice President Joe Biden this week. “No matter how much tragedy affects you, you have to find a way forward. You have to invest in life.”

Hockley’s son Dylan was among 26 people shot to death — including 20 first-graders — last Dec. 14 inside Sandy Hook Elementary. The shooter, 20-year-old Adam Lanza used a military-style assault rifle in the Friday-morning attack that ended when he killed himself.

The shootings profoundly changed this small Connecticut community and thrust gun violence back into the national debate. Led by Obama, gun control advocates called for background checks for all gun purchasers and a ban on assault weapons and high-capacity ammunition magazines.

Hockley and other Newtown parents hastened into action, privately lobbying members of Congress for changes. New York Mayor Michael Bloomberg’s organization, Mayors Against Illegal Guns, has spent roughly $15 million this year on advertising to influence the debate. And former Arizona Rep. Gabrielle Giffords, who was shot in the head while meeting with constituents in 2011, launched a national tour calling for background checks.

Yet Congress has enacted no new gun curbs since the Newtown shooting.

The inaction in Washington underscores the ongoing potency of the NRA and other gun rights groups, opposition from most Republicans and the reluctance of many Democrats from GOP-leaning states to anger voters by further restricting firearms.

Nearly eight months since the Senate rejected expanded background checks for gun buyers — the year’s foremost legislative effort on the issue — Majority Leader Harry Reid, D-Nev., hasn’t found the five votes he would need to revive the measure. He has said he won’t revisit the bill until he has the 60 votes he would need to prevail.

Says Connecticut Gov. Dan Malloy: “I was repulsed by the inability of the Congress of the United States to deal with reality.”

But there is little sign of resentment or resignation from the most prominent gun control groups. They’re re-doubling their efforts before next fall’s elections.

The head of Bloomberg’s organization says that the billionaire New York mayor is installing paid staff in more than a dozen states expected to take up gun control legislation next year to complement a robust Washington lobbying operation and television ads.

“In 2012, the mayor spent about $10 million or so dipping his toe in the water. I guess we’ll find out what the whole foot looks like in 2014,” said Mark Glaze, Mayors Against Illegal Guns’ executive director.

Giffords’ also promises to be a major player, despite health limitations. Her group, Americans for Responsible Solutions, has created a nonprofit and political action committee on pace to raise more than $20 million before the midterms, according to group officials.

“You can’t have 20 first-graders murdered in their classroom, and have a country that’s done nothing about it and just think the issue’s going away,” says Giffords’ husband, former astronaut Mark Kelly. “We’re going to keep the press on.”

Hockley belongs to a group called Sandy Hook Promise, which recently started a campaign to recruit 500,000 parents nationwide to join its effort before this week’s anniversary. They’re enlisting the help of celebrities such as including Sofia Vergara, Ed O’Neill and Alyssa Milano.

Yet there’s division even among like-minded groups over whether to push for background checks or a less-contentious mental health bill.

Sandy Hook Promise now is focusing more on mental health. Bloomberg is pushing aggressively for background checks. And Giffords’ group wants both, although Kelly says he has low expectations for background checks in the short term.

Like other Newtown parents, Mark Barden is undeterred.

“We’re trying to change the culture, and you don’t do that in a couple of months or a couple of years even,” says Barden, who lost his 7-year-old son Daniel in last year’s shooting. “All my eggs are in this basket from now on. I have an obligation to my little Daniel.”