Driven by Bartlett's friend Grover Norquist, the founder and president of Americans for Tax Reform, Republican members of Congress are urged - or bullied - into signing a pledge to support endless tax cuts.

This mantra of cutting taxes in any circumstances, rather than setting policy in response to economic realities, is more akin to religious belief than sound policy-making, Bartlett says.

"And I don't think it is a coincidence that the Republicans have become the party of religious fundamentalism," he says, arguing that once you have accepted a set of ideas that are founded in belief rather than reason - such as in one's religious life - it is easier to transpose similar thinking to other politics.

This is why, he says, many in the new right believe ideas that seem preposterous to those who live outside its circles.

"In a recent poll only 31 per cent of Republicans believed Barack Obama was born in the United States.

"Who are the others? They are either stupid or crazy."

These others, he says, get their news entirely from right wing media, which magnifies their dislocation from the real world.

Anyone within the party who challenges the dogma is ostracised, he says.

"It's like the Middle Ages where people were jailed for saying the Earth revolved around the sun."

Bartlett's own ostracism dates back to 2005 when he was sacked by the National Centre for Policy Analysis for his criticism of George W. Bush.

David Frum, the Bush speech-writer who gave us the term "axis of evil" in the 2002 State of the Union address was forced out of the conservative think tank The American Enterprise Institute in 2010 after he dared challenge the campaign against President Obama's healthcare reforms.

It was not that he entirely supported "Obamacare", just he thought the blanket opposition was poor politics, and improving America's healthcare system was a goal noble enough to warrant some compromise.

Writing in New York Magazine last year, Frum explained, "I've been a Republican all my adult life. I have worked on the editorial page of The Wall Street Journal, at Forbes magazine, at the Manhattan and American Enterprise Institutes …

"I believe in free markets, low taxes, reasonable regulation, and limited government … But as I contemplate my party and my movement in 2011, I see things I simply cannot support."

He wrote that he left the party machine thinking, "I want no more part of this cycle of revenge".

Unlike Bartlett, who says the leaders of the new populism are driven by self-interest and cynicism, Frum says many of them believe their own angry message.

"Some of the smartest and most sophisticated people I know - canny investors, erudite authors - sincerely and passionately believe that President Barack Obama has gone far beyond conventional American liberalism and is willfully and relentlessly driving the United States down the road to socialism," he writes.

"No counter evidence will dissuade them from this belief: not record-high corporate profits, not almost 500,000 job losses in the public sector, not the lowest tax rates since the Truman administration.

"The billionaires [funding the party] do exist, and some do indeed attempt to influence the political process … Yet, for the most part, these Republican billionaires are not acting cynically. They watch Fox News too, and they're gripped by the same apocalyptic fears as the Republican base."

Bartlett believes the drive towards populism can be traced partly to the Bush strategist (and Romney fund-raiser) Karl Rove, who realised it was easier to outrage the core of your political base to make them more likely to turn out on polling day than it was to broaden it.

"How do you do that? … by scaring the shit out of stupid people."

The conservative journalist and former paratrooper Michael Fumento wrote his treatise against what he calls the new right for Salon.com in May.

He described how after writing that global warming was real (while stating he did not believe there was an economically viable response) he was likened to the Unabomber, Ted Kaczynski, as well as Charles Manson and Fidel Castro in a series of billboards paid for by a conservative think tank he had done work for, the Heartland Institute.

"I … founded a conservative college newspaper, held positions in the Reagan administration and at several conservative think tanks, and published five books that conservatives applauded," he wrote.

"I've written for umpteen major conservative publications - National Review, the Weekly Standard, The Wall Street Journal and Forbes, among them.

"But no longer. That was the old right. The last thing hysteria promoters want is calm, reasoned argument backed by facts. And I'm horrified that these people have co-opted the name "conservative" to scream their messages of hate and anger."

Fumento fulminates against both the voice and the message of the new right. He laments that Mitt Romney allowed a question suggesting President Obama should be tried for treason to pass unchallenged at a town hall meeting.

He castigates the Florida Republican Allen West for saying that he estimated there were "71 to 78" Democrats in Congress who were members of the Communist Party. (Joe McCarthy claimed to know of only 57.)

And he rails at the recently deceased blogger and new right hero Andrew Breitbart, who was caught on camera in February bellowing for a minute and a half at peaceful protesters, "You're freaks and animals! Stop raping people! Stop raping people! You freak! You filthy freaks! You filthy, filthy, filthy raping, murdering freaks!"

Fumento argues true conservative ideology not only demands open debate but civil debate.

"Ever-consummate gentlemen like Buckley and Ronald Reagan would have been mortified by such behaviour as Breitbart's - or West's or Heartland's," he writes.

Speaking with the Herald Fumento says such abuse "prevents people from sitting down together and negotiating, and you cannot have a democracy without that process".

The revolt against the new right has been echoed in the elected ranks of the Republican Party. In May, the former California governor Arnold Schwarzenegger wrote in the Los Angeles Times "in the current climate, the extreme right wing of the party is targeting anyone who doesn't meet its strict criteria''.

Senator Olympia Snowe criticised the new right earlier this year when she announced she would not seek re-election.

So far, Mitt Romney seems unwilling or unable to challenge the new orthodoxy, says Bartlett. He says Romney's record as governor of Massachusetts suggests he was a moderate conservative, but since he sought the presidency he challenged no positions of the populist right and recanted on many of his own.

Bartlett does not believe the November election will temper debate whatever the outcome. Indeed he fears an Obama victory could force the right to radicalise further, while a Romney victory could provoke the Democrats to adopt the same obstructionist tactics in Congress that has stalled government over this term, leading to even more years of economic stagnation.

"I don't believe our political system can stand that," he says.

"Us public policy analysts aren't meant to make comparisons with the 1930s, but it is beginning to look like the Weimar Republic.''

Fumento's view is equally bleak, though he looks to the Bible for analogy.

"If King Solomon was in the United States today and threatened to kill the baby, you know what the Democrats and Republicans would say?

"They'd say cut the little bastard in half."

Correction: The original version of this story named Allen West as Andrew West and Bruce Bartlett as Brett Bartlett.