Fate has a way of humbling those who like to make predictions, especially political ones. So instead of trying to squeeze a column out of guessing what might happen during the Democratic Convention, I’ll employ a similarly hackish device: offering free advice to the opposition. Those articles are just as easy to write, and they leave no embarrassing residue of erroneous speculation for future critics to cite. Of course, I’m sure John Kerry will never see my advice, and if he does, I hope he doesn’t take it; I shudder at the thought of a president who—in the midst of a war against al Qaeda and the other hydra heads of radical Islam—would submit our foreign policy for review by France, Germany and corrupt U.N. bureaucrats.

Nevertheless, I’ve got a column to write, and I’m already more than a paragraph into this one, so I guess I’ll keep going. Here’s my unsolicited advice for John Kerry: run fast and far away from the extremists among your supporters. If there’s one thing that will cost you the election, it’s the folks who think President Bush is a greater threat to this country than al Qaeda, that he’s evil incarnate, equivalent to Hitler, maybe worse.

Of course, the comparison is ludicrous to anyone who knows history. Hitler tried to conquer all of Europe and exterminate an entire race of people. His actions were responsible for killing tens of millions. Drawing the comparison between Bush and Hitler is not only absurd, it’s an insult to the memory of the people Hitler killed, and a slap in the face to the millions of Americans who support President Bush with honorable intentions. When I hear someone make that comparison, I immediately know I can disregard anything else they might have to say about politics...and I’m sure I’m not the only one.

But on the left, the extremists have stolen the megaphone from the sensible, and the leaders of the movement are pretending not to notice. When the previous presidential nominee of the Democratic Party compares President Bush’s supporters to Hitler’s brownshirts, it’s quite clear that the message of the hard left has crossed over into common usage among the party faithful.

At the moment, Kerry’s base of support isn’t large enough to guarantee him victory. So, to win, he needs to convince a substantial portion of the currently undecided to back him. The loudness of the radical left isn’t helping. Even though Kerry himself has never invoked the Hitler comparison, plenty of people who support him have. That can do real political damage; after all, what effect does it have if the person telling you that “Bush is Hitler” is also asking you to “Vote for Kerry”?

It may not seem fair to tar Kerry because he has a vigorous group of extremists among his supporters. While Kerry is an unabashed liberal (despite his recent attempts to retreat from that label, his voting record is well-documented), he does not seem to be an extremist himself. But, in politics, perception matters. So does the company one keeps. At the moment, the rhetoric coming from the left is dominated by the people who truly believe that President Bush is a direct ideological descendent of Adolf Hitler.

So far, Kerry hasn’t made any attempts to distance himself from that element among his supporters. Now, you may say that as a matter of principle, he shouldn’t have to, and you’d be right. Likewise, Bill Clinton didn’t have to issue a public rebuke of Sister Souljah in front of a largely black audience when he first ran for president in 1992. But he did, and it proved to be one of the seminal political maneuvers of the campaign season.

If Kerry’s carried towards the election on the shoulders of zealots, will undecided voters wonder whether he’s a zealot, too? Well, if you routinely walk down the street surrounded by a crowd of raving lunatics, good luck trying to convince bystanders that you’re not really one of them.

Kerry needs his own Sister Souljah moment, where he unequivocally condemns the harsh, hate-filled tone that’s infected the Democratic party. He had a chance to do it recently, after his widely criticized Radio City Music Hall fundraiser. But instead of speaking out against the venom spewed by his celebrity supporters, Kerry waited a few days before sending out his campaign spinners to issue limp non-denunciations.

Kerry will have another opportunity at the convention, and this time he’ll have a much larger audience. The big question—one that will shape the rest of this race—is how the public will perceive the Democratic Convention. Whenever moderate voters see ugly anger captured on TV, they’re repelled by it. Don’t think so? Then ask the Democrats in Minnesota what happened after they turned the Paul Wellstone memorial service into a political shriek-fest. Ask the Republicans what happened after Pat Buchanan declared cultural war at the 1992 Republican Convention.

It might seem like bad political math for Kerry to risk upsetting such a loud segment of his constituency. But think about it: the people who’ve spent the last few years imagining similarities between Bush and Hitler aren’t all of a sudden going to vote for Bush if Kerry scolds them a little. Their hatred for Bush is so strong that they’d suffer any slight quite gladly if they thought it would lead to his defeat. And while Ralph Nader might be attractive to some from the standpoint of ideological purity, nobody honestly thinks that a vote for Ralph Nader would help remove Bush from the White House.

What Kerry needs to do is attract some of the voters who don’t equate Bush with Hitler. That’ll be hard if Kerry is seen as surrounded by extremists. Maybe Kerry recognizes this but is trying to have it both ways, as he does when he votes in favor of bills before he votes against them. But this is an issue he can’t waffle on. When voters view the Democratic Convention, they’ll either see hatred on display or they won’t. I’m sure Kerry’s team will do their best to present a sanitized convention, but today’s Democrats seem to be driven by rage and not reason. And rage is very hard to contain, which means we may be in for a rather interesting week up in Boston.