The political center is dead in America. And if it isn't dead, it's at least on life support.

Far-right House Republicans just prevailed over the party establishment in what most analysts consider a fruitless, politically suicidal move in which the GOP threatens to shut down the government to force Democrats to defund ObamaCare. But the seemingly outlandish idea that Republicans would shutter federal agencies — or worse, let the country default on its debt — is now par for the course. Republicans engage in this sort of political hostage-taking all the time.

But conservatives are not alone in veering toward the fringes and refusing to compromise. In the Democratic Party, the resurgent liberal wing reasserted itself recently when a coalition of women's groups, progressive populists, and affluent liberal donors helped sandbag the nomination of Larry Summers to head of the Federal Reserve. There would be no compromise.

Still, the biggest evidence of the center's seeming collapse is in the Republican Party. Arizona Sen. John McCain, seemingly talking to a conservative choir comprised of Clint Eastwood's empty chairs, warned of the far-right's quixotic kill-ObamaCare quest: "I can tell you that in the U.S. Senate, we will not repeal or defund ObamaCare. We will not. And to think we can is not rational." Rep. Peter King: "Whether it's Custer, whether it's kamikaze, or whether it's Gallipoli or whatever, we are going to lose this."

The New York Times' Paul Krugman argues that the GOP has simply rebranded itself from being "the stupid party to being the crazy party." He says it has been a decades-long process:

First came the southern strategy, in which the Republican elite cynically exploited racial backlash to promote economic goals, mainly low taxes for rich people and deregulation. Over time, this gradually morphed into what we might call the crazy strategy, in which the elite turned to exploiting the paranoia that has always been a factor in American promote the same goals. But now we're in a third stage, where the elite has lost control of the Frankenstein-like monster it created. [The New York Times]

This dismays longtime political pros like National Journal's Charlie Cook:

It's clear that perhaps 50 to 100 House Republicans see President Obama and Democrats as inherently wrong, almost evil; and thus they view compromising as essentially becoming coconspirators with evil...While this point of view is fine for the coffee shop or Rotary Club back home, it is anathema to the legislative process, where compromise is essential to making government work. Compromise is part of democracy. On some issues, digging in your heels doesn't cause a lot of harm, but on others, it is downright dangerous. [National Journal]

It's not just ideological purity that has driven the Republican Party so far right that moderates, centrist Republicans, and centrist Democrats are beginning see it as a party of extremist ideologues — and why Karl Rove warns the GOP that it risks losing independents. It's also due to sheer political expediency.

It's about trying to channel and use far-right political paranoia for electoral gain. It's about co-opting the originally bipartisan and anti-neocon Tea Party movement. And it's about kowtowing to the powerful microphones of far-right talk show hosts seeking ginned-up partisan outrage to deliver a demographic group to advertisers. It's the flip side of John F. Kennedy's Profiles in Courage — now perfectly epitomized by a finger-held-up-to-the-base-wind House Speaker John Boehner, the most inept speaker in American history.

It's gotten so bad in the GOP that, as The Washington Post's Eugene Robinson notes, "House members who balk at jumping off the cliff risk being labeled 'moderate,' which is the very worst thing you can call a Republican — and the most likely thing to shorten his or her political career."

Is the "moderate middle" becoming the "missing middle"? Throughout American history, the center refined conservative and liberal proposals and helped build consensus between the two camps. A weak or nonexistent center just means more political crises, more damaging partisan battles, and more inaction on much-needed issues. It brings to mind a comment that President Dwight Eisenhower made in 1963: "Only Americans can hurt America."