Most U.S. House members from Tennessee belong to an increasingly influential behind-the-scenes group that prides itself on staking out the most conservative of conservative positions.

Once a week, six of the seven Republican representatives from the state come to a meeting on the ground floor of the Capitol that starts with a prayer and then launches into a robust discussion of how to accomplish conservative legislative goals.

It's known as the Republican Study Committee, and it has become so big -- 175 of the chamber's 232 Republican members belong -- that the Republican leadership cannot afford to ignore it, even when its positions put the party at risk of falling out of step with the public at large, congressional experts say.

One instance of the latter, some say, came in October.

"It's because of the RSC that the government shutdown happened," Duke University political scientist David Rohde said in an interview.

The study committee was only willing to continue funding the government if the Affordable Care Act was significantly modified.

On its website, the group says, "When others look for the easy road, we're here to do what's right . . . We are here to get government out of the way."

Although the committee has existed for more than 40 years, its membership and influence increased dramatically after the wave election of 2010 that sent dozens of tea party members to Congress.

The National Journal, a public policy magazine, called the RSC "the cabal that quietly took over the House."

It added: "Members consider themselves conservatives first and Republicans second. They did not come to Washington to play for the Republican team; they came to fight for conservative principles. If that means voting against party interests, so be it. For core RSC believers, ideological purity trumps legislative accomplishment. Period."

Tennessee members are Reps. Diane Black of Gallatin, Marsha Blackburn of Brentwood, Scott DesJarlais of Jasper, Stephen Fincher of Frog Jump, Chuck Fleischmann of Ooltewah and Phil Roe of Johnson City.

Blackburn and Black frequently appear at RSC news conferences.

"It's a great place for legislative information in general," DesJarlais said. "It's a great place to go for an hour or an hour and a half. '

Blackburn said the meetings "are a chance to bring out great ideas."

But political analysts such as Norm Ornstein of the American Enterprise Institute say inflexible positions taken by RSC members contribute to the gridlock that dominates Washington

"It still espouses a radical ideology," he said. "If the leadership were to cross the Republican Study Committee, they would have real trouble on their hands."

And Rohde said, "They have constrained the speaker's freedom of action."

At least a dozen members of the RSC wanted to remove Speaker John Boehner of Ohio from his position when the 113th Congress started in January. Boehner later had to go to the committee "on bended knee" to restore harmony among House Republicans, National Journal said.

Tennessee members, however, say its unfair to label it a no-compromise group.

"I wouldn't throw that blanket over everybody," DesJarlais said. "A lot of great debate takes place. You get multiple sides of every argument."

And Blackburn said, "I don't think it makes compromise harder. It enriches debate."

As to its influence on House leadership, RSC Chairman, Rep. Steve Scalise of Louisiana acknowledged, "We try to move them in a direction that's more conservative."

Also in regard to policy, Scalise said the group's membership believes firmly that "the details matter."

Other Tennessee members join DesJarlais and Blackburn in praising the RSC's legislative role.

"Congressman Black came to Washington to take on the major challenges of the day, and the RSC helps craft bold solutions to tackle important issues like out of control Washington spending, and protecting Americans from the disastrous effects of Obamacare -- issues that are of core concern to Congressman Black's constituents," said spokesman Tom Flanagin.

Roe, meanwhile, led RSC members this fall in drafting a "conservative, market-based alternative" to the President Barack Obama's health insurance reform law. Roe's bill has more than 100 cosponsors and the backing of many conservative interest groups.

Similarly, Roe said, the committee has established other "transparent working groups that encourage conservatives who have a wide array of views to develop consensus that can stand as a rallying point against the tax, borrow, and spend approach advocated by the president and his allies."