SYNOPSIS:

In the 2000 election, in a campaign that seemed driven more by vanity than by any realistic political vision, Ralph Nader did all he could to undermine Al Gore — even though Mr. Gore, however unsatisfying to the Naderites, was clearly a better choice than the current occupant of the White House.

Now the Democratic Party has its own internal spoilers: candidates lagging far behind in the race for the nomination who seem more interested in tearing down Howard Dean than in defeating George Bush.

The truth — which one hopes voters will remember, whoever gets the nomination — is that the leading Democratic contenders share a lot of common ground. Their domestic policy proposals are similar, and very different from those of Mr. Bush.

Even on foreign policy, the differences are less stark than they may appear. Wesley Clark's critiques of the Iraq war are every bit as stinging as Mr. Dean's. And looking forward, I don't believe that even the pro-war candidates would pursue the neocon vision of two, three, many Iraq-style wars. Mr. Bush, who has made preemptive war the core of his foreign policy doctrine, might do just that.

Yet some of Mr. Dean's rivals have launched vitriolic attacks that might as well have been scripted by Karl Rove. And I don't buy the excuse that it's all about ensuring that the party chooses an electable candidate.

It's true that if Mr. Dean gets the nomination, the Republicans will attack him as a wild-eyed liberal who is weak on national security. But they would do the same to any Democrat — even Joseph Lieberman. Facts, or the lack thereof, will prove no obstacle: remember the successful attacks on the patriotism of Max Cleland, who lost three limbs in Vietnam, or the Saddam-Daschle ads.

Mr. Dean's character will also come under attack. But this, too, will happen to any Democrat. If we've learned anything in this past decade, it's that the right-wing scandal machine will find a way to smear anyone, and that a lot of the media will play along. A year ago, when John Kerry was the presumptive front-runner, he came under assault — I am not making this up — over the supposed price of his haircuts. Sure enough, a CNN host solemnly declared him in "denial mode."

That's not to say that a candidate's qualifications don't matter: it would be nice if Mr. Dean were a decorated war hero. But there's nothing in the polling data suggesting that Mr. Dean is less electable than his Democratic rivals, with the possible exception of General Clark. Mr. Dean's rivals may well believe that he will lose the election if he is nominated. But it's inexcusable when they try to turn that belief into a self-fulfilling prophecy.

Let me suggest a couple of ground rules. First, while it's O.K. for a candidate to say he's more electable than his rival, someone who really cares about ousting Mr. Bush shouldn't pre-emptively surrender the cause by claiming that his rival has no chance. Yet Mr. Lieberman and Mr. Kerry have done just that. To be fair, Mr. Dean's warning that his ardent supporters might not vote for a "conventional Washington politician" was a bit close to the line, but it appeared to be a careless rather than a vindictive remark.

More important, a Democrat shouldn't say anything that could be construed as a statement that Mr. Bush is preferable to his rival. Yet after Mr. Dean declared that Saddam's capture hadn't made us safer — a statement that seems more justified with each passing day — Mr. Lieberman and, to a lesser extent, Mr. Kerry launched attacks that could, and quite possibly will, be used verbatim in Bush campaign ads. (Mr. Lieberman's remark about Mr. Dean's "spider hole" was completely beyond the pale.)

The irony is that by seeking to undermine the election prospects of a man who may well be their party's nominee, Mr. Lieberman and Mr. Kerry have reminded us of why their once-promising campaigns imploded. Most Democrats feel, with justification, that we're facing a national crisis — that the right, ruthlessly exploiting 9/11, is making a grab for total political dominance. The party's rank and file want a candidate who is running, as the Dean slogan puts it, to take our country back. This is no time for a candidate who is running just because he thinks he deserves to be president.

Originally published in The New York Times, 1.2.04