Energized by Senate votes, pro-gun groups pledge "extensive war" on gun control Last month, four months after the Newtown, Conn., shootings kicked off a renewed battle over U.S. gun laws, gun control advocates were dealt a devastating blow: After months of behind-the-scenes negotiations, bipartisan dinners and personal presidential entreaties, the Senate voted down a measure that would have expanded background checks for U.S. gun buyers, scuttling the primary gun law thought to have a fighting chance to make it through at least one - if not two - bodies of Congress. For pro-gun groups like the National Rifle Association (NRA) and the Gun Owners of America, both of which had been working hard behind the scenes to make sure the measure didn't have sufficient support to gain Senate passage, the Senate's actions marked a critical victory. The overarching Senate gun bill was tabled, and gun control advocates found themselves scrambling, after months of work on the so-called Manchin-Toomey compromise, to find a new path forward. The extent to which the NRA and the gun lobby can take credit for the Senate vote is debatable, but as the NRA convenes Friday for its annual meeting in Houston, its message is clear: "Our theme here is stand and fight," said NRA spokesman Andrew Arulanandam, in an interview with CBSNews.com. From our perspective, this is not over. This is a fight that will take years. And what happened a couple of weeks ago [in the Senate] was the first battle in what will be many battles. But we're prepared for a very long and extensive war. In the coming years, the pro-gun lobby and its opposing groups will both face critical tests to their political weight: In the 2014 midterm elections, both have vowed to target those lawmakers who defy their ideological will; whether or not the NRA and its allies or groups like Mayors Against Illegal Guns, a pro-gun control group, are more successful in advancing their agendas will likely be a harbinger of the future of gun laws. So far, Gun Owners of America likes its odds. "The fact that gun control was stopped in the Senate we feel that, at least so far, that our efforts have been very successful," Erich Pratt, the communications director of Gun Owners Of America, told CBSNews.com. We certainly don't want to pop the cork before the Congress adjourns but we actually felt confident all along - cautiously optimistic - and I think, after the defeat in the Senate a couple weeks ago, even more so now. According to Pratt and Arulanandam, the aftermath of the Newtown massacres - after which point the White House made a concerted push for new legislation strengthening the nation's gun laws - has served as a source of inspiration for their supporters, fueling hundreds of thousands of new signups and renewed enthusiasm. "Our membership has grown by almost a third - it was at 300,000, and so we're almost at 400,000," Pratt said. We've definitely seen people's concern and people wanting to be active and I think that's probably the most exciting thing: Activism has been way up. Both his group and the NRA claim the bulk of their strength comes from their grassroots activism, and Arulanandam dismissed as "one-sided and unfair" the common Democratic charge that the NRA holds lawmakers hostage on votes related to gun control. "The NRA has a fiduciary responsibility to our members and to our supporters, and that is to make sure that we help elect representatives who will protect the Second Amendment for them and for future generations, that has always been our mission, it's been our mission for over 140 years, and we make no apologies for that," he said. The way we run our operations is no different than any other interest groups including the gun control lobbies. Gun control activists have at least one major quibble with this charge: Josh Sugarman, executive director of the Violence Policy Center and author of the book NRA: Money, Firepower & Fear (also a native of Newtown), argues that, in the face of a decade-long trend of dropping membership, the NRA has instead relied on the gun industry for its funding - and has become a mouthpiece for its interests rather than for those of its members. "The NRA is a gun industry trade association masquerading as a shooting sports foundation," he told reporters in a conference call. Mark Kelly, the husband of former congresswoman and gun violence victim Gabrielle Giffords, echoed that sentiment in an op-ed Thursday in the Houston Chronicle. Guns fly off the shelves after tragedies because LaPierre and the gun manufacturers he represents exploit people's fears. In return, gun manufacturers gave LaPierre and the NRA tens of millions of dollars last year alone - and he spent almost $1 million of it on his own salary," Kelly wrote. Everyone in the gun lobby gets rich when the gun manufacturers sell the most guns. And that's why LaPierre and the rest of the leadership of the NRA and other gun organizations are spending so much of their time wild-eyed, preaching possible government confiscations. Gun control advocates point to polls showing gun owners broadly supporting background checks as signs of dissent within the ranks of NRA membership. But at the annual conference today, Sugarman says, the chances those internal fissures will be up for discussion is "zero." Even as the NRA plans for an "extensive war" against gun control, its advocates see signs of hope in the weeks since the failure of the Manchin-Toomey amendment: In recent weeks, some politicians - including Sen. Jeff Flake, R-Ariz. - have suggested their poll numbers have dipped as a result of their gun votes. Earlier this week, Sen. Kelly Ayotte, R-N.H., a moderate Republican from the northeast, was confronted at a town hall meeting by the daughter of the Sandy Hook principal who was gunned down while trying to protect her students at their elementary school. She, along with five other adult faculty members and 20 first grade students, was killed. Democrats hope sinking poll numbers and bad publicity can help inspire the necessary five lawmakers to change their votes, which would enable Senate Majority Leader Harry Reid, D-Nev., to revive the bill on the Senate floor. Sen. Joe Manchin, D-W.Va., who co-authored the bill, says he hopes to have another vote before August. "We're going to pass this thing," he said last week on "Fox News Sunday." Don't give up. Toomey, his Republican co-sponsor, was less optimistic about the measure's prospects. In the end it didn't pass because we're so politicized. There were some on my side who did not want to be seen helping the president do something he wanted to get done, just because the president wanted to do it," Toomey told The Mercury newspaper. It's a pretty heavy lift to get five senators to change their mind on a big issue like this... It's not likely to happen any time soon. I hope people will reconsider over time. So far, no second vote is scheduled, and the chances that it will have a second life are unclear. But at the very least, Kelly is calling on members of the NRA to demand a change of guard. "When LaPierre and his crew of highly paid Beltway insider staff reversed their earlier support of common-sense measures like expanded background checks, they sent a strong message that instead of standing with the 3 million of your members who supported background checks, they were working on behalf of the manufacturers' profit margins instead," he wrote. It seems to me that the time is right for a new generation of leaders within the NRA.