All sanity seems to have left the ranks of those in charge of the GOP. Increasingly, it is becoming clear that the party is against everything and for nothing. That's not governing. That's just lobbing hand grenades. And the GOP is shrinking daily before our eyes.

But those aren't my words. That stinging assessment comes courtesy of Mark McKinnon, a Texas-based Republican consultant and adviser to George W. Bush.

At this point in the fiscal-cliff crisis, with House Republican ideologues seemingly so willing to plunge America over the precipice, there is indeed no need for me to state the obvious. I can just quote the sane Republicans, as they assail their unhinged brethren. For instance, here's Congressman Steven LaTourette of Ohio, lamenting the tax-phobic conservatives who refuse to face fiscal reality:

"It weakens the entire Republican Party. ... It's the continuing dumbing-down of the Republican Party, and we are going to be seen more and more as a bunch of extremists."

And as a result, we now have a crisis of governance.

There's no sane reason why President Obama and Congress can't compromise on a year-end budget deal that raises taxes on top-bracket Americans (while preserving the Bush-era middle-class cuts), and slices into federal spending. Obama has already offered those terms - a tax hike on people earning $400,000 or more (his original proposal was $250,000), plus an array of spending cuts deep enough to tick off the Democratic left. But the House GOP rank and file said no.

House Speaker John Boehner tried to woo his rank and file with "Plan B," proposing a tax hike on millionaires. But again his recalcitrant troops said no. Most Americans believe that a high-end tax hike is essential to any compromise - every poll says so - and Obama won reelection after campaigning on that premise. In fact, the Gallup poll released Wednesday reports that 54 percent of Americans endorse Obama's handling of the fiscal-cliff crisis. The congressional GOP's approval rating is 26 percent.

But House conservatives don't care. They're adamant that the rich should never be compelled to dip into their pockets for the betterment of all.

McKinnon, in his post the other day, ruefully wrote: "It's a very odd situation when the losing party is the party refusing to negotiate. It may be how you disrupt, but it is not how you govern." Fellow Republican strategist John Weaver tweeted in disgust, after Plan B went down, that Boehner is stuck with the impossible task of "herding cats on crack."

It appears that the cats haven't grasped the lesson of that Lincoln movie, which reminds us that compromise is the oil in the governing engine. In the absence of compromise, the engine breaks down. Without a year-end budget deal, two million Americans will immediately lose their federal jobless benefits, and middle-class taxes will rise (among other consequences). And all the polls agree that if we do a cliff dive, congressional Republicans will get the brunt of the blame.

So why are these House people behaving so self-destructively?

Many hail from safe districts where conservative voters dominate. Norman Ornstein, scholar at the conservative American Enterprise Institute, calls these districts "homogeneous echo chambers." The incumbents are virtually guaranteed reelection - as long as they toe the conservative line. If they were to compromise, they risk being challenged in primaries. As the purist group Club for Growth remarked last week, "the only thing that motivates members of Congress is fear of losing their jobs."

Actually, there is one other big motivator: slavish fealty to the one-percenters who bankroll the party - and who are hostile to paying higher taxes.

So says Mike Lofgren, who spent 16 years as a Republican senior analyst on the House and Senate budget committees. He saw the party's fealty to the rich up close. He quit last year because, in his words, "my own party, the Republican Party, began to scare me." From his new book:

"The GOP cares, over and above every other item on its political agenda, about the rich contributors who keep them in office. This is why tax increases on the wealthy have become an absolute Republican taboo.... The GOP's mission is to protect and further enrich America's plutocracy. The party's caterwauling about deficits and debt is so much eyewash to blind the public."

The crisis of governance might be alleviated if more Republicans spoke that way. Hopefully, some absolutists are still reachable. They should heed Mark McKinnon: "We become a stronger Republican Party by acting like reasonable human beings who acknowledge reality."

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Dick Polman is a columnist for the Philadelphia Inquirer.