The people who are moved by their contempt for George W. Bush could find themselves in the position of doing a lot to help George W. Bush this fall.

And the people who feel the same sentiment for John F. Kerry could do a lot to elect the Democratic nominee.

All that may seem unlikely on the surface, but the way Bush opponents channel their dislike for the president will go a long way toward determining whether he wins a second term or finds an uneasy, unexpected retirement in Crawford, Texas. And the way Kerry opponents channel their fury toward Kerry could help determine whether he becomes yet another Bay State politician to seek the White House and fail.

This is the first campaign of a generation in which the conduct and strategic choices of both candidates’ supporters could shape the outcome.

Democrats face more danger

By far the greater danger is on the Democrats’ side. And though the campaigns are worrying about soccer moms and NASCAR dads and the Catholic vote and the prayerful vote, the new group of Bush haters — a onetime coalition of the willful — could emerge as an important factor in the November balloting.

These voters could swing the election by what they do and by what they don’t do. If they remain an important presence in the streets — appearing as protesters at the president’s rallies, conducting marches down city streets with flag-draped coffins meant to symbolize needless war casualties — they could play directly into Republican hands. They would allow the president to portray his opponents as unpatriotic elitists unwilling to support American men and women in uniform in war zones.

And if they don’t vote for Kerry in November — if, like so many thousands of their brethren in 2000, they cast a vote for the purity of Ralph Nader instead of swallowing the imperfections of Kerry — they could throw the election to Bush. They did precisely that last time. Look, for example, at the tiny state of New Hampshire, which the candidates fight so desperately over in January but ignore in September. Do the math, and you’ll see that if you add only a third of Nader’s 2000 vote to Vice President Gore’s vote in the state, Gore is the winner — not only of New Hampshire, but also of the White House.

Turnout is key

In a close election, as we learned to our horror in Florida four years ago, everything is a factor, and every vote counts. That’s why turnout is so important, and why both parties are investing so much energy, money and manpower to making sure their supporters get to the polls. If the 2004 election is a referendum on the president (and all re-election campaigns are), then the people who want most to deny the president a second term are an especially powerful group.

Powerful, if they are rational. Nader’s critique of the 2004 election — the notion that Bush preys on the nation’s fear of terrorism and Kerry preys on the Democrats’ fear of Bush — may be appealing to some of these Bush haters but ultimately destructive to the only candidate with a reasonable chance of defeating the president.

It’s not only the Democrats who have a problem with the passionate among them. The Republicans do, too. Religious conservatives might ordinarily be considered the president’s closest allies; he is, after all, one of them. But doctrinal differences too infinitesimal to measure by outsiders have left some of these religious conservatives cold, or made them feel left in the cold, and the White House is worried about turnout among these voters.

‘Angry man’ may detract

It is also becoming clear that the rhetoric of the angry may turn out to be the rhetoric of the alienating.

Last week, Sen. John McCain, the Arizona Republican whose embrace of the president has become ever tighter, suggested that high-octane political speeches like that of Sen. Zell Miller could backfire on the Republicans. Miller is the Democratic senator from Georgia who delivered the keynote address at the Republican National Committee and — another example of how a candidate’s supporters can motivate his opponents — has emerged as a get-out-the-vote treasure for Democrats who feel they have been cuckolded politically by one of their own.

Then there is the risk that members of the Christian right, troubled by the drift of the administration, could push Bush on subjects important to the social-issues wing of the Republican Party and neutralize the president’s effort to appear more compassionate than conservative in the last seven weeks of the campaign.

There is, in short, a danger in feeling too strongly.

This wouldn’t be the first time that smart people have behaved stupidly in presidential elections. John Mueller, an Ohio State political scientist, has written that the anti-war movement in the Vietnam years helped defeat Vice President Hubert H. Humphrey in his campaign against former Vice President Richard M. Nixon in 1968.

“Some of the most vocal war opponents actively expressed their rage by trashing Humphrey’s campaign (but not Nixon’s), by shouting him down and displaying antagonistic banners sporting such vivid and memorable slogans as ‘Dump the Hump,'” Mueller wrote in an Internet article, adding: “A man even more hawkish on the war (was) elected president.”

Now that the general-election campaign is in full swing, the two candidates must appeal for the support of their natural allies — but at the same time seek to rein in their natural allies. It is a difficult task, but one that is more difficult for Kerry than for Bush. It is the Democrat, after all, who is unfamiliar and whose trustworthiness is unknown. It is Kerry whose supporters have another place to land if they grow angry with the mainstream candidate. It is Kerry who is the challenger, and whose challenges are greater than those of his opponents.

David Shribman is a columnist for Universal Press Syndicate.