It's been asked before, but it's worth asking again: If Democrats and Republicans share the blame for Congress's stupendous incompetence, which is a widespread and rather facile presumption here, then what is the Democratic Party's equivalent of the Tea Party caucus?

Is there, for example, anywhere in Barack Obama's party a bloc whose anti-gay and pro-gun views are so extreme that one of its leading members compares enacting any restrictions on gun ownership to allowing gay marriage and bestiality? (Louie Gohmert, Republican, Texas)

Or, whose members would travel to Egypt shortly after its generals arrested a democratically elected president, and then killed at least 1,000 of his protesting supporters, to declare on television that "We're here as members of Congress to say 'We're with you. And we encourage you.'" (Michele Bachmann, Republican, Minnesota).

Or, who would proclaim that 99 per cent of illegal migrants in America spend their time hauling marijuana around, that immigrants should be chosen the way you choose a good dog, and that the border fence with Mexico should be electrified, because "we do that with livestock all the time." (Steve King, Republican, Iowa).

The Republicans have about 40 of these characters in Congress at the moment, a small band of extremists who in the name of ideological purity are now threatening to shut down and essentially bankrupt the U.S. government.

You actually have to feel some pity for the GOP establishment, which probably has much greater reason to fear their own internal freak show than do the Democrats.

The Tea Partiers are a dog-wagging tail of flamethrowers, evidently intent on blowing up their own party's leadership, and destroying the government in order, in their view, to save it.

Obamacare obsession

Actually, one suspects the Democrats are privately cheering them on.

Having come to prominence in 2010 amid the furor over Barack Obama's health-care plans, Tea Party supporters are stepping up their battle again this year, with rallies like these on Capitol Hill earlier this month. (Jonathan Ernst / Reuters)

And why not? Why interrupt your political opponents when they are running around airing public doubts about the extent of rape, or constantly alienating the ever-growing Latino community?

But when they take steps to shut down the federal government, as the House Republicans are now doing, and deprive people of crucial services (and probably jobs) at a time of fragile economic recovery, well, that's entirely another order of political craziness.

So is forcing a catastrophic default on U.S. debt obligations, which is exactly what the Tea Party worthies are now rushing toward.

Their stated goal — apart, presumably, from showing Americans how much better off they'd be without central government — is to destroy the Affordable Care Act, known here as Obamacare. It's their obsession.

"Aren't you embarrassed?" asked Democrat John Dingell in August, as House Republicans voted for the fortieth time (seriously, the fortieth time) to repeal Obamacare.

The answer, of course, is no, despite the fact that repeal is a fantasy. Obamacare is the law of the land. It was passed four years ago, when Democrats briefly controlled both the House of Representatives and the Senate.

Obamacare has withstood a constitutional challenge, and thunder will curdle milk before Senate Democrats or the White House kill the president's signature political achievement.

Showdown time?

Most Republicans understand that. A lot of them have said so.

The U.S. Chamber of Commerce, a conservative lobby if there ever was one, says the current GOP threats are against the interests of business and of the American people.

The Wall Street Journal's deeply conservative editorial board predicts the willingness to shut down government will shut Republicans out of power: "Kamikaze missions rarely turn out well."

Bush-era Republican guru Karl Rove has warned the move will weaken the party with voters, and strengthen Obama.

Republican Senator Richard Burr of North Carolina has called the fixation on killing Obamacare "the dumbest idea I've ever heard."

The response? Tea Party-related groups have retaliated with negative election ads against party dissenters, whom they call RINOs (Republicans In Name Only), or have "primaried" Republican incumbents, blocking their nomination at the party level.

Among their current targets is Mitch McConnell, the Republican leader in the Senate.

House Republicans, terrorized, have now fallen into line.

After Tea Partiers revolted recently against a compromise proposal by Speaker John Boehner (another Tea Party punching bag) the entire caucus, with only one dissenter, voted for a bill that will cut off government funding by Oct. 1 unless Obama agrees to dismantle his health-care law.

The Democrat-controlled Senate will almost certainly return that bill this week, with the references to Obamacare stripped out. And the American government will be just that much closer to shutdown.

Safe seats and local politics

Tea Partiers are also licking their chops at the prospect of an even more important deadline: Sometime in mid-October, the government will need to borrow more money in order to keep paying the debts incurred by previous congresses.

This newest budget showdown comes as Federal Reserve chairman Ben Bernanke, to the surprise of most observers, decided last week to continue the central bank's stimulus program, an indication the U.S. economic recovery is still to fragile to begin pulling back. (Gary Cameron / Reuters)

Tea Partiers oppose raising the debt ceiling to allow that. They would prefer to provoke a default on government debt, which would shatter the faith and credit of the United States.

The U.S. Treasury bill is the world's platinum standard for safe investment. Allowing default would almost certainly mean a spike in interest rates, which would be disastrous to homeowners and businesses nationwide, never mind the U.S. government or markets worldwide.

National interest? Pa-tooey.

As Thomas Massie, a Tea Party Republican from Kentucky, put it: "All that really matters is what my district wants. And my district is overwhelmingly in favour of my position."

There's a reason for that smugness. Because of artful gerrymandering and creative voting rules at the state level, Tea Partiers tend to be less vulnerable to voter punishment than many of their colleagues in Congress.

"Most are in safe seats," says Thomas Mann, a Brookings Institution fellow and co-author of It's Worse Than It Looks: How the American Constitutional System Collided With The New Politics of Extremism.

"They are ideological zealots and populists who believe their mission is to save the country and banish the infidel president. Eventually, the public will make them pay, but not before the damage is done."

Norman Orenstein, a scholar at the right-leaning American Enterprise Institute, is the book's other author.

He says Tea Party politicians "want a massive revolution, and if that means upheaval and catastrophe in the short term, and election losses, that is preferable to compromising. They have in part been convinced by their own self-reinforcing wind machine that default would be fine. It is not just suicidal, it is homicidal."

The current Congress has been the least productive in American history. Mann and Orenstein, in their book, say it's time to recognize Republican obstructionism as the cause.

The public though, has so far reacted with irritation and benumbed indifference. People seem to think the threats of government shutdown and default are just histrionics.

Perhaps. But it may not be a good idea to underestimate ideologues bent on glory.