A supporter of Republican presidential candidate Mitt Romney holds an NRA baseball cap during at a campaign rally in Craig, Colo., in May.

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This week, some of the victims of that shooting rampage at a Colorado movie theater were laid to rest. In the days following the attack, the country's political leaders offered expressions of sorrow for the lives lost. But none moved to rewrite laws, in hopes of preventing such massacres.

Election-year politics may be one explanation. But as NPR's David Welna reports, another may be the sway one interest group holds over Congress.

DAVID WELNA, BYLINE: Earlier this week, Colorado congresswoman Diana DeGette joined three other Democratic lawmakers at the Capitol to make a plea.

REP. DIANA DEGETTE: We don't believe that the Second Amendment guarantees somebody the right to walk into a movie theater with a semiautomatic weapon, and a hundred-round ammo magazine, and shoot 71 people. We don't believe that. And we believe that we need to have a national conversation.

WELNA: One that the Denver-based Democrat hoped would begin on Capitol Hill. But there's virtually no chance such conversation would lead to action. Here's John Boehner, the Republican House speaker, on Thursday, when asked whether new laws were needed to prevent another gun slaughter.

REP. JOHN BOEHNER: You know, I think that what's appropriate at this point, is look at all the laws that we already have on the books; and to make sure that they're working as they were intended to work.

WELNA: On the other side of the Capitol, Senate Democratic Leader Harry Reid was also giving a thumbs down.

SEN. HARRY REID: With the schedule we have, we're not going to get into debate on gun control.

SEN. FRANK LAUTENBERG: The silence is almost deafening.

WELNA: That's New Jersey Democratic Sen. Frank Lautenberg. He blames the 4-million-member National Rifle Association for stifling any congressional action on guns.

LAUTENBERG: And we cannot let the NRA stop us from commonsense reforms anymore.

WELNA: Gun-control advocates say the NRA's power cannot be overestimated.

MIKE CASTLE: I believe the NRA has as much sway on Capitol Hill as any lobbying group in the country.

WELNA: Mike Castle is a former Republican congressman from Delaware.

CASTLE: They've done a very effective job of convincing people that - whether it's true or not - convincing people that, you know, they have the power to completely limit their futures in elected office, if they don't cooperate.

WELNA: Most recently, the NRA has been weighing in on an ongoing fight between Republicans and Attorney General Eric Holder, regarding a gun-tracing operation known as Fast and Furious.

(SOUNDBITE OF A POLITICAL AD)

UNIDENTIFIED ANNOUNCER: Did America's top prosecutor commit perjury before Congress? Call the president, tell him to fire Eric Holder. Paid for by the men and women of the National Rifle Association.

WELNA: When the House moved late last month to hold the attorney general in contempt of Congress, the NRA announced the vote would count in its ratings of lawmakers. Seventeen Democrats joined all but two of the House Republicans, in approving the contempt citation. Here's NRA legislative director Chris Cox after that vote.

CHRIS COX: So my hat's off to those Democrats who bucked their party, bucked their president; and put truth and justice over politics.

WELNA: Minnesota's Tim Walz has an A-rating with the NRA. He's one of the Democrats who voted to hold the attorney general in contempt. Did he fear the NRA might work against his re-election bid this fall, had he voted differently?

REP. TIM WALZ: No, I can't say whether they would've or not. But again, I would have to assume that that very well could have happened.

WELNA: But some say the NRA's power has been vastly overestimated. Mark Glaze directs the advocacy group Mayors Against Illegal Guns.

MARK GLAZE: People are hard-pressed to find more than a handful of members of Congress who have ever lost their seat because of the NRA, or because of a gun vote. But the NRA has spent a lot of money, and a lot of years, building up that very reputation. And a lot of Democrats have bought into it.

REP. GERRY CONNOLLY: I'm not intimidated by anybody.

WELNA: House Democrat Gerry Connolly has the NRA's headquarters in his Northern Virginia district. Nonetheless, he believes his advocacy of stricter gun laws has helped him win re-election. Still, Connolly understands how many colleagues bend to a reality of politics.

CONNOLLY: That which is perceived, is also real. So the power exercised here - certainly, by the NRA - is considerable.

WELNA: The NRA was asked to comment for this story, and declined.

David Welna, NPR News, the Capitol.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.