If Howard Dean wins the Iowa caucuses, the Democratic presidential race is over.

Take all the noise to the contrary from other candidates and the news media, who have vested interests in keeping the race alive, with a large grain of salt.

A Dean win in Iowa would require an unprecedented series of events to deny the former Vermont governor the nomination. It would also mark the first time that Iowa’s peculiar form of democracy really has settled a nomination fight.

While a scenario to stop Dean if he wins Iowa might exist in some screenwriter’s mind, there is none in the real world of politics.

History says candidates who have the most money, highest poll numbers and strongest organization win unless they get knocked off early in the small, retail campaigning states.

No one can come close to Dean in New Hampshire’s Jan. 27 primary, where the race is for second place. That leaves only Iowa on Jan. 19.

The only one who can beat Dean in Iowa is Richard Gephardt of Missouri, the former House Democratic leader who won there in 1988 but ran out of gas once the voting moved from his neighboring state. He trails Dean there but is within hailing distance.

Gephardt must catch Dean in Iowa for there to be some, albeit small, chance that anyone other than Dean can become the party’s standard-bearer against President Bush.

The chances of stopping Dean even if he loses Iowa are small because he is so far ahead in New Hampshire and well positioned to run nationally, while the others are competitive only in certain states.

A second-place finish in Iowa for Dean might only mean his eventual New Hampshire margin of victory will be less than 20 points. Gephardt is not a serious contender in New Hampshire, and even winning Iowa won’t change that.

But if Dean wins Iowa, his train will be off and running down the track to the nomination, and everything else will just be political theater.

After New Hampshire, the campaign goes wholesale. The numerous contests scattered throughout the country will be won based on a candidate’s ability to convince voters through television commercials, organizational strength and media coverage.

Those are categories in which Dean is the best positioned. Moreover, most of the others will be broke at that point and none, other than perhaps Gephardt if he wins Iowa, will be getting a cash infusion from donors impressed by a winner’s vote-getting power.

If Dean does win Iowa, everyone else will be just going through the motions, despite the virtual certainty that an ABD (anyone but Dean) candidate will emerge from the Iowa and New Hampshire also-rans.

Whether Gephardt, Sens. John Kerry of Massachusetts, John Edwards of North Carolina, Joseph Lieberman of Connecticut or former Gen. Wesley Clark, the eventual ABD candidate will argue that Dean is not only unelectable, but will be a drag on Democrats running for other offices.

They may be correct. There are many, myself included, who think Dean is the reincarnation of Walter Mondale and George McGovern combined, each of whom only carried one state when they faced the voters in November. Like 1984 nominee Mondale, Dean is pledging to raise taxes massively ($3 trillion), while Dean’s strong opposition to Bush’s Iraq policy is reminiscent of McGovern’s 1972 campaign against the Vietnam War.

Regardless of the eventual accuracy of those crystal balls, the ABD forces can’t possibly succeed if Dean wins Iowa, because such a victory would eliminate Gephardt as a contender.

There are two loyal party constituencies critical to a successful ABD effort under even the most favorable circumstances — blacks and organized labor.

There is no serious contender for the Democratic nomination (sorry Al Sharpton and Carol Moseley Braun, you don’t fit that definition) around whom blacks can logically coalesce.

And Gephardt, whose opposition to free trade floats labor’s boat, is the only candidate with serious union support other than Dean.

If Iowa voters sideline Gephardt, the other unions, like many blacks, are very likely to jump on Dean’s bandwagon because his anti-war, pro-tax increase, socially liberal agenda is more in tune with theirs than any potential ABD candidate.

So when Iowa Democrats brave subfreezing temperatures to gather in their town halls, churches and living rooms, this year for the first time they may actually pick the nominee rather than just narrow the field as they have done in the past.

Peter A. Brown is an editorial page columnist for the Orlando Sentinel. His e-mail address is pbrown@orlandosentinel.com.