And while the party’s growing extremism condemns it to seemingly permanent minority status  Mr. Schwarzenegger was and is sui generis  the Republican rump retains enough seats in the Legislature to block any responsible action in the face of the fiscal crisis.

Will the same thing happen to the nation as a whole?

Last week Bill Gross of Pimco, the giant bond fund, warned that the U.S. government may lose its AAA debt rating in a few years, thanks to the trillions it’s spending to rescue the economy and the banks. Is that a real possibility?

Well, in a rational world Mr. Gross’s warning would make no sense. America’s projected deficits may sound large, yet it would take only a modest tax increase to cover the expected rise in interest payments  and right now American taxes are well below those in most other wealthy countries. The fiscal consequences of the current crisis, in other words, should be manageable.

But that presumes that we’ll be able, as a political matter, to act responsibly. The example of California shows that this is by no means guaranteed. And the political problems that have plagued California for years are now increasingly apparent at a national level.

To be blunt: recent events suggest that the Republican Party has been driven mad by lack of power. The few remaining moderates have been defeated, have fled, or are being driven out. What’s left is a party whose national committee has just passed a resolution solemnly declaring that Democrats are “dedicated to restructuring American society along socialist ideals,” and released a video comparing Speaker of the House Nancy Pelosi to Pussy Galore.

And that party still has 40 senators.

So will America follow California into ungovernability? Well, California has some special weaknesses that aren’t shared by the federal government. In particular, tax increases at the federal level don’t require a two-thirds majority, and can in some cases bypass the filibuster. So acting responsibly should be easier in Washington than in Sacramento.

But the California precedent still has me rattled. Who would have thought that America’s largest state, a state whose economy is larger than that of all but a few nations, could so easily become a banana republic?

On the other hand, the problems that plague California politics apply at the national level too.