When House Majority Leader Eric Cantor walked out of the debt-ceiling negotiations last week in a hissy fit, he once more dramatized the simple truth that cannot speak its name. This Republican Party is addled by an extremist ideology and cankered by a vengeful partisanship. In a time of national crisis, it is locked into ideological litmus tests — no new taxes — and opposed to anything the “Kenyan, socialist” president might propose.

This makes the routine difficult and the necessary impossible. Republicans threaten to blow up the world economy by refusing to lift the debt limit without getting drastic cuts in the deficit. Puffed up with locker-room bravado, they set a high bar — more than $2 trillion in deficit reduction over 10 years, a dollar or more for every dollar hike of the debt limit.

But Cantor detonates the talks because, in fact, Republicans won’t negotiate on how to reach their goal. They will accept no new taxes, no closing of tax loopholes, no crackdown on overseas tax havens. The richest 400 Americans enjoy a lower tax rate than their cleaning women, but their taxes cannot be raised. The biggest corporations, such as General Electric, pay little or no taxes on billions in profits, yet their loopholes cannot be closed.

So the entire $2 trillion must come from spending cuts. But Republicans also won’t agree to mandated cuts in defense spending, despite the fact that the defense budget has soared since Sept. 11, two unfunded wars contributed trillions to the debt, and the Pentagon is one of the nation’s leading sources of waste, fraud and abuse. Some Tea Party members suggest that defense spending is on the table, but the negotiators oppose any separate cap for defense spending, leaving the issue in the hands of the very appropriators who have regularly insisted on spending more than the Pentagon asks for.

Republicans are so strait-jacketed by their “pledge” never to raise any taxes that any Republican suggesting the closing of subsidies to big oil or ethanol makers? is considered a profile in courage. And now, the conservative arch-druid Sen. Jim DeMint adds a new litmus test for any presidential candidate: He or she must not only embrace the no-tax pledge but promise to pass a constitutional amendment to balance the budget. This inanity, left over from Newt Gingrich’s 1994 “Contract With America,” will now be a feature of Republican presidential debates.

Not that the Republican field, now in full-body pander to its base, will have trouble saluting. It seems in a rush to the ridiculous. Former Minnesota governor Tim Pawlenty, reputed to be one of the “adults” in the field, put out an economic plan that features a repeal of all taxes on corporations, additional deep cuts in tax rates for the rich and a “Google test” for dismantling government (that is, if any good or service can be found on the Internet, the government should let the private sector provide it). He asserted that 5 percent growth would result, eventually bringing the budget into balance, so he happily signed up for the DeMint pledge.

Former Massachusetts governor Mitt Romney, the GOP front-runner, showed his conservative leg, denouncing financial reform and claiming that “banks are afraid to make loans right now because of the government hanging over them like gargoyles.” After collecting $1 million in contributions in the wake of a speech wooing Wall Street donors, Romney chided those pushing for stricter regulation for acting “as if Wall Street greed is something new.” He didn’t bother to mention what should be done to keep that greed from blowing up the economy again.

Whatever they are drinking at the Tea Party, they’re getting loonier. Michele Bachmann, the self-declared head of the Congressional Tea Party caucus who officially launched her presidential run Monday, has announced that the debt limit should not be raised, no matter what. She’s denounced the Americorps national service program as an attempt to build “re-education camps for young people, where young people have to go and get trained in a philosophy that the government puts forward.”

Bachmann also became so alarmed by the fantasy that the Treasury Department was conspiring to abandon the dollar that she introduced a resolution to “bar the dollar from being replaced by any foreign currency.” Surely, standing strong to prohibit the Obama administration from abandoning the American flag and the national anthem is next. Bachmann’s wing-nut tendencies, however, don’t keep her from being one of the favorites in the Iowa caucuses.

Senate Minority Leader Mitch McConnell epitomizes the irresponsibility of today’s Republican Party. He is proudly and reflexively anti-anything Obama. McConnell has cheered House Republican efforts to gut funding for the financial regulatory agencies, arguing that “anything we can do to slow down, deter or impede their ability to engage in this kind of oppressive overregulation would be good for the country.”

McConnell summarized the Republican message for the election in 2012: Obama inherited a poor economy but made it worse. Given the Republicans’ threat to blow up the economy over the debt limit, their opposition to any sensible measure to boost the economy and put people to work, their efforts to gut even weak financial regulation, it is hard to avoid the conclusion that Republicans have moved from rooting for a bad economy to use in running against Obama to actively committing to making it worse.