The problem for Hillary Clinton that arises from the incident in which a disturbed man invaded her Rochester, New Hampshire, campaign headquarters is not any kind of physical threat. Clinton is the most carefully-managed and thoroughly-secured presidential candidate since Ronald Reagan, who when he began to show the first signs of the dementia was placed in a sort of protective custody during the 1984 campaign. Clinton is is no greater danger now than she has been in since the start of her campaign; and neither, thankfully, were her New Hampshire supporters, who exited the headquarters without injury.

The problem for Clinton is a political one.

The incident in Rochester reminds prospective Democratic primary voters and caucus-goers that the front-runner for the party’s presidential nomination is a celebrity candidate who attracts controversy, who is legitimately seen as divisive and who– barring a major shift in tone and style — will always campaign at a distance from the American people.

This is not entirely fair to Clinton. She has indeed been the victim of the “vast right-wing conspiracy” that she named after millionaire conservatives and their paid minions defining her as a cruel and conniving egomaniac who would stop at nothing to obtain power and position.

But there is nothing fair about American politics. And, while Clinton has made some progress when it comes to softening her image, she has not begun to transform herself so successfully as did the “ruthless” Bobby Kennedy in 1967 and 1968 — or even the “boring” Al Gore in the period since he ceded the presidency to George Bush.

Hillary Clinton remains a charged figure who excites great passions. She is a highest-profile politician whose fame is both blessing and curse. The blessing is that, without offering much more than platitudes, she has been able to wink and nod her way to the top of most Democratic polls. The curse is that, if an desperate man in Rochester, New Hampshire, is looking for a campaign headquarters to invade, it’s going to be Clinton’s.

If a few other desperate men target the Clinton campaign in coming weeks — or even a desperate woman as hyped up as the one who called the Democratic senator a “bitch” at a recent John McCain event — the contender who so recently seemed inevitable will be in trouble.

It’s won’t be Clinton’s fault, at least not wholly. But incidents of this kind will make Democrats, who think they have a good chance of winning the presidency in 2008, start asking: Why invite the volatility that goes with Hillary Clinton? Why not nominate someone — a John Edwards, a Barack Obama, even a Bill Richardson — who provokes a little less passion?

To deny that such thinking will go on in the heads not just of pundits but of grassroots Democrats would be absurd as the calculus that said John Kerry was the most electable Democrat of 2004.

The challenge for Clinton, then, is not to avoid the issue. She must confront it. She must turn her volatility to her advantage. She should take a risk that puts her outside the comfort zone of her own campaign — and of contemporary politics. She should speak bluntly about the bitter partisanships, the crude tactics, the open hatreds that now characterize campaigning and that so undermine the ability of elected leaders to govern in a functional, let alone inspiring, manner.

The incident in Rochester was not a big deal. It was overplayed by the media. Clinton and her aides are safe, as safe as any serious presidential contenders and their hangers on. But the Friday’s headquarters invasion got the attention it did for a reason. Everyone recognizes the emotions — both positive and negative — that Hillary Clinton inspires. And everyone suspects that they could boil over again, either physically or politically.

Clinton needs to address her perception and her reality as a remarkable political figure who has already made a great deal of history and could make a great deal more. She cannot do it with spin. The reliance on spin, on managed messages and manipulated moments, is a big part of what Americans — even some of her supporters — distrust about her.

Hillary Clinton needs to open up. She needs to speak frankly. She needs to acknowledge that, for better or worse, she inspires intense reactions. She needs to start talking about that intensity. And she needs to explain to the American people — if she can — how that intensity, as opposed to silly spin about “bringing us all together, is what this country needs after George Bush’s sleepwalk across the minefield.

If Clinton does this, it will not matter what passions play out during the course of the coming campaign. She will be on her way to the Oval Office. If she fails to do so, Clinton will remain vulnerable to the incidents that are all but certain to unfold, and that vulnerability will beg questions that could well cost her the presidency.