Welcome to Congress in the echo-chamber age, where outside influencers have an increasing sway on how Members shape their agenda.

At a time when Rush Limbaugh reaches as many people as vote in Florida and California combined, and when Jon Stewart can draw several hundred thousand people to the nation’s capital, these outsized personalities based far outside the Beltway have become as much a part of Washington’s political ecosystem as the lawmakers themselves.

This phenomenon was most prominent during the long health care debate but has been seen again vividly in the weeks following the Tucson, Ariz., shootings, during the Republican transfer of power and as President Barack Obama prepares his budget.

With Members taking cues from the echo chamber as well as their party leadership, it’s changed the way business gets done. Limbaugh and Fox News hosts Glenn Beck and Sean Hannity can mobilize more voters than any press release or floor speech, so Members find themselves needing to be responsive or face their wrath.

A Republican strategist and former top Republican National Committee aide told Roll Call that Members have one of two reactions when constituents start a message with “I just heard on Rush today …” — “joy and panic.”

Limbaugh has more than 20 million listeners, and most Members couldn’t dream of their message being so widely spread back home, the GOP strategist said.

“You’ve got to break eggs to make an omelette, and if you’ve never been mentioned on these shows in either a favorable or less than favorable context, one has to wonder, are you actually making an impact?” the strategist said.

If Limbaugh or Beck pushes an issue, his audience picks up the phone and taps out e-mails, asking lawmakers to take action. “These Members understand that their constituents are listening to this, and the consequence will elicit action that will place pressure on them,” the strategist said.

Ron Bonjean, who was a top aide to then-Speaker Dennis Hastert (R-Ill.) before the Democratic takeover in 2006, said outside influences have ballooned at almost warp speed over the past few years.

“It used to be that if Rush said something on the air and the Washington Times wrote an editorial, it was earth-shattering. But now there is so much competition and [Members] are hearing from a lot more voices,” Bonjean told Roll Call.

Bonjean said Republicans frequently assert their independence from conservative talkers, but he admitted, “The show hosts definitely have an influence over the decision-making of leaders.”

The liberal watchdog group Media Matters has compiled examples of Limbaugh and Fox themes that made it from the airwaves to the floors of the House and Senate.

After Fox replayed “sting” videos showing alleged fraud at the Association of Community Organizations for Reform Now, then-Minority Leader John Boehner (R-Ohio) introduced a measure to cut ACORN’s government funding. Rep. Pete Olson (R-Texas) wrote a resolution honoring James O’Keefe and Hannah Giles for producing the ACORN videos, and 31 of his GOP colleagues signed on. It never received a vote.

When Beck suggested on his show in June that an Obama administration drilling decision helped liberal billionaire George Soros, two Republican Members repeated the claim using similar language on the House floor. Limbaugh called the BP oil spill fund set up last year a “slush fund,” a term repeated by Members in television appearances and during floor debates.

With the addition of the tea party movement to the national conversation, the spin cycle has added a setting that could be labeled “outrage.” Ideas that hosts use to gin up their base go from television to the House floor to the cardboard signs displayed by tea partyers on the National Mall.

“The ecosystem of each ideological movement within the political parties is much bigger than just the elected officials,” said Simon Rosenberg, a veteran of Bill Clinton’s White House who now leads the progressive group New Democrat Network.

Rosenberg identified religious groups, community organizations, labor unions and activist outlets such as MoveOn.org as holding more influence over the agenda. On the left, he sees MSNBC, progressive blogs and Stewart’s Comedy Central as dramatically changing the conversation in Washington, and he said their influence has increased in recent years.

Late last year, Stewart used “The Daily Show” to advocate the passage of the 9/11 responders bill. It was going nowhere but somehow was resurrected in the eleventh hour of the lame-duck session after his show highlighted first responders in a highly rated segment.

Several Republicans privately admitted Members carefully monitor what’s being said on conservative airwaves to make sure they aren’t contradicting it or enraging talkers.

Democrats needled the GOP in early 2009 over whether Limbaugh was actually the leader of the Republican Party. When then-RNC Chairman Michael Steele said Limbaugh was an “entertainer” and not one of the party’s leaders, he was forced to apologize after days of negative headlines and backlash on Limbaugh’s show. Steele relented: “There was no attempt on my part to diminish his voice or his leadership.”

When the rest of the Republican establishment was chastising Rep. Joe Wilson for his “You lie!” outburst in September 2009 as Obama addressed a joint session of Congress, Limbaugh hailed him and said he was “irritated” party leaders didn’t support Wilson.

In the days following the Arizona shootings, political talkers found themselves at the end of pointed fingers. Former Alaska Gov. Sarah Palin (R) went on the defensive after Internet activists suggested she played a role in inciting anger during the elections. A few on the left promised to tone it down, and Beck mocked Media Matters for asking Fox to hold his show accountable. But little changed and hosts on both ends of the political spectrum cranked coverage back up to detail Palin’s reaction and to analyze whether political Washington was being too politically correct.

MSNBC host Rachel Maddow told Roll Call she believes the right “has long had a wider-reaching, more fully-formed messaging apparatus than the left.”

“It may be that there’s more rightwing media echo in their politics simply because the right’s echo-chamber works better,” Maddow said in an e-mail. “Comparatively speaking, messaging on the left is much more ad hoc, much less disciplined and repetitive, and much less wide-reaching.”

Rosenberg and other Democrats agreed there’s a less cohesive message on the left. Several said efforts by MoveOn to influence Democratic leadership end up providing fodder for conservatives in that ecosystem, proving the right’s echo chamber is more effective.

“It always seems that if you turn on Hannity or Beck or Limbaugh, you seem to be hearing the same things come from Representatives’ and Senators’ mouths in the next 24 hours,” said Stefan Hankin, a Democratic strategist. “The voices on the left just don’t have the same drumbeat.”