"This is not a battle about gun rights," incoming president James Porter said in a brief speech, calling it "a culture war."
"(You) here in this room are the fighters for freedom. We are the protectors," he said.
NRA Executive Director Chris Cox praised the organization's efforts to defeat the gun control bill.
"It was great to see the president throw a temper tantrum in the Rose Garden," Cox said.
Conference attendees Debbie and Daniel Ferris agreed with Porter's assessment.
"It's about fighting tyranny," Debbie Ferris said.
The conference is in Texas, one of the strongest gun rights states in the country. Gov. Rick Perry once bragged about shooting a coyote during a morning jog. Concealed handguns are allowed in the state Capitol.
Gun control advocates say they will have a presence around the convention, with plans for a vigil for victims of gun violence, a petition drive to support background checks for gun purchases and a Saturday demonstration outside the convention center.
Sandy Phillips, whose daughter was killed in the Colorado theater mass shooting in July 2012, met privately with Cruz this week. She said Cruz refused to budge on expanding background checks on gun purchases and told her he considered it the first step toward government confiscation of guns.
"They're always good at saying the right thing, 'I'm so sorry for you loss and da da da da da,"' Phillips said. "If you're really sorry for my loss, do something about it."
Despite polls that show most Americans favor some expansion of background checks, Ladd Everitt, spokesman for the Coalition to Stop Gun Violence, said a big challenge is matching the NRA's grassroots organizing.
"The NRA knows this issue is very much in play. People were sickened by that Senate vote," Everitt said.
Despite their loss in Congress, gun control advocates have scored significant victories at the state level. Lawmakers in Colorado passed new restrictions on firearms. Connecticut added more than 100 firearms to the state's assault weapons ban and now requires background checks for private gun sales. Maryland and New York have passed sweeping new gun laws.
"There have been significant victories (at the state level). We expect that to continue, and we're not giving up on the federal level," Everitt said.
- AP