By Greg McCune

ST. LOUIS (Reuters) - U.S. presidential hopeful Mitt Romney vowed to gun owners on Friday he would reverse what he called the restrictive gun policies of President Barack Obama.

Romney, who has fumbled when talking about his experience with guns, took up the cause of sportsmen and other gun owners in an address before the annual convention of the National Rifle Association in St. Louis, Missouri.

It was Romney's first speech to a major conservative group since his closest rival for the Republican nomination, Rick Santorum, suspended his campaign this week. That cleared Romney's path to take on Obama, a Democrat, in the November 6 general election.

The former Massachusetts governor needs to win over conservatives, many of whom are gun owners, but they have shown limited enthusiasm for him.

"We need a president who will stand up for the rights of hunters, sportsmen, and those seeking to protect their homes and their families," Romney said. "President Obama has not. I will." His campaign released the remark before Romney spoke.

Romney's NRA appearance comes during a nationwide debate over gun rights and race after the Florida shooting of an unarmed black teenager, Trayvon Martin, by neighborhood crime watch volunteer George Zimmerman.

A Romney campaign official said Friday that decisions surrounding "Stand Your Ground" laws - which allow people to use deadly force when they believe their lives are in danger - should be left to individual states. Florida's version of the law has come under attack in the Trayvon Martin case.

Romney dismissed the Obama administration's handling of gun rights, saying the White House operates outside of the original vision for American government.

'SO UNAMBIGUOUS'

"This administration's attack on freedom extends even to rights explicitly guaranteed by our Constitution," Romney said. "The right to bear arms is so plainly stated, so unambiguous, that liberals have a hard time challenging it directly. Instead, they've been employing every imaginable ploy to restrict it."

A Reuters/Ipsos poll released Thursday showed that 68 percent, or two out of three respondents, had a favorable opinion of the NRA, which lobbies against limits on gun ownership.

Eighty-two percent of Republicans saw the gun lobbying group in a positive light as well as 55 percent of Democrats, findings that run counter to the perception of Democrats as anti-NRA.

But the poll also showed strong support for some gun controls including background checks, limiting the sale of automatic weapons and keeping guns out of churches, stores and workplaces.

Romney has stumbled when talking up his hunting prowess. At a debate in South Carolina in January, the former Massachusetts governor said he last went hunting for moose in Montana. Then he quickly corrected himself, saying elk were, in fact, the target.

In 2007, Romney drew laughs when he said he was a "small varmint" hunter.

"I'm not a big-game hunter. I've always been a rodent and rabbit hunter. Small varmints, if you will," he said at the time.

During his unsuccessful 2008 run for the nomination, Romney said he did not walk in lockstep with the NRA.

"I support the work of the NRA. I'm a member of the NRA. But do we line up on every issue? No, we don't," Romney told NBC's "Meet the Press."

Roger Palmer, an NRA member and an information technology manager from High Ridge, Missouri near St. Louis, said he and his wife were having trouble getting excited about Romney.

"I don't have a lot of enthusiasm for him," Palmer said. "I have to make a decision whether to vote."

(Reporting by Greg McCune in St. Louis and Lily Kuo in Washington; Writing by Samuel P. Jacobs; Editing by Vicki Allen)