One way or another, the U.S. will deal with its budget deficit. It’s unavoidable. The job could be done intelligently, gradually and without fuss, by adopting a few undrastic measures, or it could be left until the roof falls in and all the choices are bad. Congress is thinking, let’s go with the roof option.

Nobody in Washington is much surprised by this. Still, it presents a puzzle. By Europe’s standards, solving the U.S. budget problem is easy. Gentle remedies of the kind proposed by the Simpson-Bowles deficit-reduction commission are all that’s needed. Yet Washington prefers to fail. Abjectly. This calls for explanation.

Let’s not reject the obvious reason just because it’s obvious. The polarization of American politics is the proximate cause, at least. In the U.S. constitutional order it is difficult, and meant to be difficult, to do anything, including budget policy, without compromising. Lately the ideological center in Congress has thinned, and the distance between the parties has widened. Compromise has come to be seen as surrender -- and the U.S. government has all but come to a halt.

Voters watch and say they don’t like it. Their disapproval of Congress sets records, and they tell pollsters they want the parties to stop squabbling. Centrist voters, disproportionately important in deciding elections, are especially exercised on the point. So here is the deeper puzzle: Why doesn’t either party respond? In electoral terms, what makes them think that polarization pays?

One school of thought says that voters only think they want compromise. If they saw it, they wouldn’t like it -- and they don’t care about budget deficits as much as they say. The Simpson-Bowles mixture of tax increases and entitlement cuts would be intensely unpopular, on this view. Electorally, it makes better sense for Democrats to defend entitlements above all and for Republicans to oppose tax increases above all, and for both sides merely to pretend (like voters) to care about the deficit.

I don’t believe it. I have a higher opinion of voters. Most of them, I think, would support the Simpson-Bowles approach if it were offered to them and properly explained. Somebody ought to try it, at least.

My own theory of U.S. political paralysis is not that a deeply divided electorate is getting what it asks for, but that the balance of power between party leaders and activists has moved too far in favor of activists. This leaves the center disenfranchised. Activists are not ordinary people. They are devoted to politics, but many care more about staying true to their principles than winning elections. They are disinclined to compromise, energetic and generous with their time and money.

The influence of the Tea Party on Republicans is self-evident, and so is the discomfort of the party’s leaders in Congress. The insurgents have pushed a modern Republican Party that was conservative to begin with much further to the right.

In today’s Republican Party, the individual health-insurance mandate -- quite recently a conservative idea recognizing the responsibilities of citizenship -- has become an instrument of socialism. Fiscal conservatism used to mean collecting taxes sufficient to cover public outlays. Now it means no tax increases ever, and to hell with the deficit. Now it means, “Who says default is necessarily bad?”

Activists haven’t dragged the Democratic Party to the left in the way the Tea Party has dragged the Republican Party to the right, but they have done something equally consequential: They have made it harder than it should have been to punish the new Republican extremism.

Despite popular doubts about health-care reform and the efficacy of the fiscal stimulus, the Republicans’ strides toward the lunatic fringe of American conservatism have left centrist voters there for the taking. Think what a skillful triangulator like President Bill Clinton could have done. (I’m struck by how ardently his new book, “Back to Work,” supports the Simpson-Bowles recommendations.)

Instead we have a barely visible president and a Democratic Party devoted to public-sector unions, naive anti-capitalism, the National Labor Relations Board and heavier taxes on the rich as though this were a goal in its own right rather than a regrettable necessity.

In today’s Democratic Party, the dominant intellectual strand argues that the Republicans’ transformation makes it all the more important to double down on class struggle and other core Democratic beliefs. Otherwise the Democrats might win something -- and what a tainted victory it would be. Better to wait for the clarifying “mandate” that the New York Times’ Paul Krugman said in a recent column will come “eventually.” After all, where’s the urgency?

You might reasonably ask, Is it such a bad thing that activists are exercising more and more influence? Power in democracies ought to go to the energetic and the engaged, you might say. If centrists are too lazy or confused to take part, tough luck. A fair point, but be careful what you wish for. Ask yourself whether it’s a formula for national success to have political power moving back and forth between Occupy Wall Street and the Tea Party.

Not that this is likely: U.S. elections rarely if ever yield mandates. Pending a constitutional convention, the future is stasis, and if the alternative is outright control for one side or the other, it might be the best the country can do. For the moment, anyway, this is the plan.

The consequences of the supercommittee’s breakdown won’t be instant. Their failure is supposed to trigger automatic spending cuts in 2013. If those cuts go into effect as scheduled, the result will look as though the committee did its job: $1.2 trillion of deficit reduction over 10 years. Inadequate, but better than nothing. If the cuts are canceled, as they probably will be, the risk ratchets back up -- but with Europe in even worse trouble, the U.S. may for now remain a comparative haven.

So the roof will stay on a while yet, and it’s not too late to get policy right. But can it be done? I am starting to wonder. It’s only a matter of time before the world understands something Americans already know. The fiscal problem is only part of something bigger and much worse: The country’s governance is collapsing. Once that sinks in, the roof won’t be far behind.

(Clive Crook is a Bloomberg View columnist. The opinions expressed are his own.)

To contact the author of this article: Clive Crook at clive.crook@gmail.com.

To contact the editor responsible for this article: Timothy Lavin at tlavin1@bloomberg.net.