ST. LOUIS — These should be good days for the National Rifle Assn. The nation’s leading gun group enjoys immense political power and has effectively muted the debate about the use of firearms in America.

Under its leadership, gun rights advocates have seized the legislative momentum from gun control supporters. High-profile shootings such as the Trayvon Martin case have stirred outrage but few calls for action. Polls show the public, though still divided on guns, has shifted away from broad support for further restrictions.

“I think the NRA is winning,” said Dan Gross, the new president of the Brady Campaign for gun control.

Still, as more than 65,000 NRA members gather in St. Louis this week for their annual convention, the organization sounds more worried than complacent, and faces an uncomfortable reality in the coming presidential campaign.

The NRA leadership is throwing its wholehearted support behind Republican Mitt Romney, who once incurred its ire by supporting stiff gun restrictions as governor of Massachusetts. Despite that history, it sees Romney as a vastly better gamble than President Obama, although Obama has done almost nothing to restrict gun use.

“We believe Mitt Romney would do a better job than President Obama,” said Andrew Arulanandam, a spokesman for the NRA, which claims nearly 4 million members. “We believe that any of the candidates on the Republican side would be better on the 2nd Amendment” — the right to bear arms.

Romney, an NRA member who has said he owns two shotguns and likes to shoot “varmints” such as rodents and rabbits, is among a who’s who of conservative leaders scheduled to speak to the convention Friday.

In part, Romney will be under pressure to calm uneasiness in the gun community dating to his governorship and before, when he supported an assault weapons ban and the federal Brady gun control law.

In 1994, while running for the U.S. Senate against Edward M. Kennedy, he touted those positions and said, “That’s not going to make me the hero of the NRA.” He now says he “will enforce the laws already on the books,” but does not believe the country needs more gun control.

His NRA audience will want to hear more.

“I have not heard Mitt Romney comment on 2nd Amendment rights. How strongly is he supportive?” asked Allen Swanson, 59, a retired traffic engineer from Bloomington, Ill., who is a target shooter and occasional hunter. He was chatting with two friends outside the convention hall Thursday, waiting for it to open.

“How come he won’t say where’s he’s at?” said one of the other men, Leonard Beach, a 47-year-old carpenter and NRA life member from Heyworth, Ill. Gun rights, he said, “should be part of the conversation” in the presidential campaign.

If Romney is not quite the dream candidate of the gun lobby, he has a trump card: He’s not Obama.

The president has certainly never been a hero of the NRA, and gun owners will not soon forget his comment in the 2008 campaign about “bitter” Americans who “cling to guns or religion.”

In this campaign, the NRA bases its opposition to Obama largely on his appointments, in particular Supreme Court Justices Elena Kagan and Sonia Sotomayor and Atty. Gen. Eric H. Holder Jr.

But more than that, the group’s leaders say they believe Obama will show his true colors as a gun control advocate only in a second term.

The last few years, Obama “concocted a scheme to avoid the gun issue,” NRA Executive Vice President Wayne LaPierre has written. The idea was to “lull gun owners into a false sense of security,” all the while “planning and plotting, behind closed doors, to launch a massive anti-gun onslaught when the time is right,” LaPierre said.

That may be intentionally alarmist, but it in some way mirrors the hopes of the Brady Campaign’s Gross.

Saying he has been disappointed in Obama’s inaction on gun control, Gross said, “I would be very hopeful that in a second term, President Obama would be more out front on the gun issue than he’s been in his first term, and it’s quite clear that Mitt Romney would not be.”

Not likely, said Adam Winkler, a UCLA law professor who wrote “Gunfight: The Battle Over the Right to Bear Arms in America.”

“Few presidents have shown as little interest in gun control as Barack Obama,” he said. “It’s as if ‘avoid gun control at all costs’ has become a plank in the Democratic Party platform.” In part because of the NRA’s success in targeting politicians who support gun control, Democrats have learned that “there are very limited gains to be had” and “high costs to be paid” by supporting it, he said.

Sen. Dianne Feinstein (D-Calif.), a longtime advocate for gun restrictions, said the NRA “essentially has a stranglehold on Congress.”

In a statement emailed by her office, Feinstein expressed frustration over the current climate, in which Congress has shown “unwillingness to pass common sense measures to reduce gun violence.” Even when one of its own, then-Rep. Gabrielle Giffords (D-Ariz.), was seriously injured in a shooting that killed six people, “Congress failed to ban the large capacity ammunition feeding device” that the suspect, Jared Lee Loughner, allegedly used, Feinstein said.

For all that, Winkler said “it’s not all peaches and cream for the NRA.”

He said the organization had “badly misfired” by failing to support a landmark Supreme Court case that led to a 2008 ruling affirming an individual right to own guns under the 2nd Amendment. The NRA had feared the case could lead to a ruling that would undermine that right.

“As a result, I think the NRA has lost respect from a lot of gun owners,” he said.

If it has lost political clout, however, it is less apparent.

“There’s no one out there who can compete with the NRA, neither in the gun rights community or the gun control community,” Winkler said. “It is an incredibly successful political powerhouse.”

mitchell.landsberg@latimes.com