Observing the Congressional Republicans repeatedly stumble in and out of their caucus clown car, blowing loud kazoos and muttering angry threats, should be painful, embarrassing and highly instructive to any American voter with the patience to watch. When their latest performance concluded late Tuesday night with a 257 to 187 vote passing the stopgap fiscal deal negotiated by the Senate and the White House, an unavoidable question lingered: What is wrong with those people?

The simple explanation is that the House of Representatives has increasingly been dominated over the past two decades by a coterie of tantrum-prone extremists, who lack the probity and steadiness required for democratic self-government. Their diminished capacity is reflected in the low quality of leadership they have chosen during this long twilight, from Newt Gingrich, Dennis Hastert and Tom DeLay to John Boehner and Eric Cantor, even as their politics have grown more and more extreme.

Under the stress of their incoherence, the Republican caucus is unable to escape one humiliating mess after another. The damage they routinely inflict on the country’s economy and future is reaching incalculable levels — and is almost certain to grow worse when they again hold the debt ceiling hostage next month.

By the end of the current episode, which is only an interlude rather than a true resolution, the top Republicans in the House had split, with Boehner casting a rare vote in favor, and House Budget Committee chair and former vice presidential nominee Paul Ryan voting yes, along with 84 fellow Republicans and almost all of the House Democrats, while House Majority Leader and would-be Speaker Eric Cantor voted no. On the floor, House Ways and Means chair Dave Camp tried to claim that this bill is “the largest tax cut in history,” although he might have difficulty explaining why more than 150 Republicans voted against it.

The Republicans’ incompetence in government is inextricably connected with their ideological extremism, as the latest events demonstrate. Hogtied by the craziness of the ultra-right Tea Party faction, the House GOP leadership cannot even cooperate with other Republicans in the Senate — who overwhelmingly voted for the “cliff” deal negotiated with Vice President Joe Biden — let alone conduct serious discussions with the White House.

Having refused to support the leadership’s “Plan B” scheme to raise taxes only on households making $1 million or more annually — despite confident claims by Boehner and Cantor that they had counted the necessary votes — the Republican caucus made both themselves and their leaders look ridiculous. It was a dreadful right-wing plan, but still much too liberal for too many of them. Tacitly acknowledging that he could no longer manage his restless wingnuts, Boehner insisted that the Senate and White House should come up with an emergency measure on their own.

Yet when the Senate leadership, including Minority Leader Mitch McConnell, offered a bill negotiated with Vice President Joe Biden — just as Boehner had urged — the House Republicans descended into crisis. Their leaders couldn’t endorse the bill, fearing that the GOP caucus crazies would defenestrate them. But they could hardly employ their usual partisan tactics to keep the bill off the House floor, after the Senate had passed it by a vote of 89-8 with only five Republican defections. They might have noticed as well their declining numbers in every public poll, with the latest Republican-leaning Rasmussen survey showing a Democratic lead in the generic congressional contest of 11 points and climbing.

Astonishingly, they nevertheless wasted several hours debating whether to amend the bill with new spending cuts and then send it back to the Senate, where leaders of both parties would have surely and justly rejected such tardy handiwork. Consistent only in their ineptitude, the House Republicans were reportedly unable to agree among themselves on exactly how to change the bill, in any case.

Finally, they folded — or at least their leaders did — and proclaimed that they were girding themselves for the battles to come over the budget and the debt ceiling, which have now been postponed for another month or so.

The deal itself is not a bad one, from the Democratic perspective, raising significant new revenues from the wealthiest taxpayers and excluding any “grand bargain” (or raw deal) to weaken Medicare, Social Security and Medicaid. Its specific provisions are still far too generous to the highest-income taxpayers and will not, in the long run, raise enough revenue to sustain decent government, rebuild the nation’s infrastructure, and prepare for the future.

The struggle over what government should do and how to pay for its functions continues, almost immediately. And perhaps soon the president and his party will explain, without hesitation, what this brief tumble over the “cliff” has shown us, and what we may hope they have finally learned: That there is no negotiating partner among the House Republicans, who must be defeated if progress is to be possible.