In a direct appeal Friday to the powerful lobbying group, Thompson, McCain and Huckabee stressed their backing for gun rights and record of siding with the NRA. Giuliani, who once referred to the NRA as "extremists," tried to explain his shifting views on the issue.
The NRA's support is prized as the group blankets its 4 million members with ads, mailings and phone calls. Before the 2008 election, it hopes to increase its numbers.
"I'd like us to respect each other; I think we have very, very legitimate and mostly similar views," Giuliani told NRA members, who clapped politely a dozen times during his 20-minute speech.
Giuliani also tried to explain why, as mayor, he joined a lawsuit by several cities against the gun industry, arguing that manufacturers and distributors made it too easy for criminals to get guns.
On Friday, he said the ongoing lawsuit "has taken several turns and several twists I don't agree with."
Giuliani, an outspoken proponent of gun control during his eight years as mayor, said Friday he agrees with a recent federal court ruling that overturned a 30-year-old ban on private ownership of handguns in Washington, D.C. He added that he would appoint judges who take a similarly strict view of the Constitution and the Second Amendment.
Despite Giuliani's changing views, NRA chief Wayne LaPierre said: "All I know is, I liked what I heard today. It's a good thing, if a politician sees the light and supports the Second Amendment."
Thompson, McCain and Huckabee chose to highlight their record on gun rights in a veiled criticism of Giuliani and former Massachusetts Gov. Mitt Romney. In 1994, Romney supported the Brady gun control law and said he wouldn't be the hero of the NRA.
Romney became a lifetime member of the NRA in 2006. He addressed the group by video Friday.
"Let me speak very directly and candidly about where I stand: I support the Second Amendment as one of the most basic and fundamental rights of every American. It's essential to our functioning as a free society, as are all the liberties enumerated in the Bill of Rights," he said.
Thompson, who makes a point of visiting gun shops and gun shows in early voting states, received a warmer reception from the audience of about 500 people, some of whom stood and cheered when he said: "Our basic rights come from God, not from government."
Thompson recently indicated that he wouldn't talk about his faith on the campaign trail.
"It's not just a matter of promises made, as far as I'm concerned. It's a matter of commitments that have been kept," Thompson said.
McCain criticized Giuliani outright, citing the use of the word "extremists" in reference to the NRA.
"My friends, gun owners are not extremists; you are the core of modern America," the Arizona senator said. "The Second Amendment is unique in the world and at the core of our constitutional freedoms. It guarantees an individual right to keep and bear arms. To argue anything else is to reject the clear meaning of our founding fathers.