It is very easy for Howard Dean (search) to predicate his primary campaign on criticizing U.S. involvement in Iraq. But it may be very hard in the general election.

Right now, he can attack the decision to intervene since he, alone among the major Democrats, neither voted in favor of the war or said he would have had he been in Congress at the time.

But campaigns are about the present and the future, not the past. You can't wage them with nothing but historical issues.

Democratic opponents of the Iraq war are fond of comparing this engagement to the disastrous conflict in Vietnam (search). But the political situation for opponents of both wars are quite different.

None of the main critics of Vietnam, certainly none of the senators, called for outright U.S. withdrawal. They spoke of euphemistic, half-measures such as "negotiate now" or halt or pause the bombing of North Vietnam. With so many dead Americans, it was not possible to speak of unilateral withdrawal (search) without being assailed for urging a solution of "cut and run."

In Iraq, there are no half measures. You can't call for negotiations: The government with which one might once have parlayed, lies dead and destroyed.

Nor, if Bush is smart, will Dean be able to pin his hopes on turning the war over to the Iraqis. Bush is giving signs that he will do so just as Dean hits the general election campaign trail. How can Dean run urging Bush to do what he is already doing?

The Iraq issue is the biggest danger to Bush's re-election. But Bush can completely neutralize it by bringing troops home week after week during the election campaign. With each new planeload, the arguments in favor of Dean will atrophy. Even if Iraqis are killing Iraqis and Baghdad and the Sunni triangle (search) are in chaos, Americans will not care as long as Saddam is not in power and U.S. forces aren't being killed.

Indeed, Dean faces the prospect of having to wage his campaign based on two elements of not-so-ancient history: the recession and the deaths in Iraq. If Bush can keep the economy growing and creating jobs even as he pulls troops out of Iraq and secures those that remain by limiting their mission, he can achieve political immunity the likes of which incumbent presidents (search) can only dream.

It is always the right of the incumbent to remove his vulnerability by solving the nation's problems in time for his re-election. Presidents that look beleaguered in the year before elections can stage big comebacks (see Clinton 1995-96), with a bit of real progress on the issues. If Bush builds a dynamic economy, is withdrawing from Iraq piece by piece and passes Medicare coverage for prescription drugs (search) on top of it all, he'll be a two-term president.

Dean, for his part, won't be able to campaign on the issues of his choice -- the economy and Iraq. As he criticizes Bush's record, he will find the solutions happening all around him. He'll be in a position akin to George McGovern's (search) in 1972 -- running as an anti-war candidate when (in Henry Kissinger's well-remembered words) "peace is at hand."

It's not a good way to get elected.

Dick Morris is a Fox News contributor and author. His latest book is "Here Come the Black Helicopters: UN Global Governance and the Loss of Freedom." Visit his website: www.dickmorris.com and follow him on Twitter@DickMorrisTweet. Click here to sign up to get all of Dick's videos emailed to you.