Tea Party lawmakers are berated as legislative arsonists and suicidal anarchists bent on sabotaging the American political system, but their very intransigence may be key to their success in an increasingly polarized Washington.

The rhetoric against the Republican Party's ultra-conservative faction reached fever pitch in the halls of Congress this week as the US government barreled into its first partial shutdown in 17 years Tuesday.

Senate Majority Leader Harry Reid, President Barack Obama's top ally in Congress, captured the Democratic disbelief about the small band of Tea Party-backed ideologues who may well hold the future of the US government in their hands as they resist efforts to pass spending bills or raise the debt limit without extracting dramatic concessions from the administration.

"Understand we are dealing with anarchists," Reid said. "They hate government."

How deep are their ranks in the House of Representatives? Between 30 and 40 of the 232 House Republicans are considered hardcore Tea Party members; anti-government, anti-tax rebels against the establishment who are ultra-conservative on social issues, religion and gun control.

Many are political novices, swept into power in 2010 on the belief that Obama's signature health care reform that was passed into law that year marked the cornerstone of a European-style socialism taking root in the United States.

Tim Huelskamp, 44, is a perfect example of this new pedigree. A farmer by profession, he holds a doctorate in political science and hails from the largely homogeneous first district of Kansas, in the heart of conservative country.

Huelskamp was elected in 2010 with 73 percent of the vote. In 2012, Democrats didn't bother to field a candidate.

For months he campaigned to link federal funding to a rollback of the Affordable Care Act. Now, under pressure from Huelskamp and his colleagues, the Republican leadership headed by House Speaker John Boehner has embraced the position.

"We're very excited," congresswoman Michele Bachmann, who founded the House Tea Party Caucus in 2010, said last Saturday, after Boehner introduced measures that would fund government only if "Obamacare" were defunded or delayed. "It's exactly what we wanted, and we got it."

Despite public opinion blaming the grand old party more than Democrats for the shutdown, lawmakers like Huelskamp remain largely immune to electoral sanction.

"As the right flank of the party grows, there are areas of the country where there is no incentive for them to worry about the national reputation of the party," said Sarah Binder, a congressional scholar and professor at George Washington University.

"It's entirely possible that the brand name does get harmed, but it's not necessarily felt if you're out in Idaho or Kansas," where Republicans dominate the political landscape.

Huelskamp boiled it down, telling AFP: "At the end of the day it's pretty hard to go home, particularly in a Republican primary, and say 'Hey, I just let Harry Reid get his way.'"

Hijacking the party

Geographic polarization is perhaps the main factor in the increasingly partisan politics, Binder said. Republicans congregate in rural areas and the Bible Belt south, while Democrats are being drawn to the coasts and the cities. In party primaries, the race has become a competition about ideological purity.

Add to this the influence of far-right groups like the Club for Growth, which rates elected officials on a conservatism scale (Huelskamp: 100 percent) and invests millions in ad campaigns against Republican moderates.

With Tea Party influence suddenly front and center in the Washington showdown, their most visible member at the moment is not in the House but in the other chamber.

Senator Ted Cruz, an upstart freshman from Texas, has sought so strongly to use the current fiscal battles to force the White House to relent on Obamacare that he has endured vitriol from both parties.

According to Professor Susan MacManus of the University of South Florida, the constant pressure of a quickening media cycle and politicized channels life Fox News and MSNBC merely widens the chasm between the two sides.

"People like Cruz and (Senator) Rand Paul, they are really taking advantage of this kind of celebrity combativeness that you see on American television," MacManus said. "It makes the whole process become less civilized."

In 1995 the Republican majority and Democratic president Bill Clinton battled to paralysis, but then-speaker of the House Newt Gingrich held sway over his members. Boehner is tame by comparison.

Now, with the Tea Party faction in the glaring spotlight, some Republicans can no longer contain their impatience with their rebel colleagues.

"I consider myself a solid conservative but I think what's happened here with the Ted Cruz Republicans is absolute insanity," congressman Peter King told CNN. "We've allowed them to hijack our party."