It is increasingly clear that President Bush's line of attack against John Kerry will be to describe him as a flip-flopping politician, changing his positions constantly to suit the political needs of the moment. One negative ad, previewed on "Meet the Press," showed an animation of two John Kerry boxers battling one another. The winner? George W. Bush.

The obvious goal of the Bush attack is to discredit Kerry and make it hard for anyone to believe in him or anything he says. But this round of flip-flop attacks is just the precursor of the main Bush offensive. Attacking Kerry for reversing himself on many key issues will weaken the Democrat, but the real point is to soften him up for two more deadly attacks likely to follow.

First, the flip-flop ads are designed to make Kerry appear too weak to lead America through the tough challenges of terrorism at home and abroad. Attacking a candidate for reversing himself on key political issues is the best way to make him appear weak, indecisive and vacillating.

When I worked for President Bill Clinton, the Republicans tried the same tactic, constantly citing his frequent reversals on issues to demonstrate weakness. Their barbs were very effective and led to a White House policy of never, never, never reversing a stand on anything.

(Sometimes, White House staff liberals took advantage of this axiom to leak word that Clinton was about to take a liberal position so as to foreclose him from doing anything else for fear of it seeming to be a flip-flop. During the welfare-reform debate, after Clinton had privately decided to sign a waiver to let Wisconsin move ahead with the work requirements and time limits its Legislature had adopted, some White House staffers leaked that he had decided to veto it instead. Terrified of seeming to flip on the issue, Clinton eventually backed off the Wisconsin proposal but then signed a national welfare-reform law. )

Bush wants to show that Kerry is too weak to lead the nation as a wartime president. It is no accident that Bush is opening his paid media campaign by reminding voters of his strong stance in the months after 9/11. He wants to raise the saliency of terrorism as an issue and to up the ante for the strength required of a chief executive. The flip-flop ads are his way of doing it.

By showing the Democrat as a man who can be pushed first one way and then the other by political winds, he shows him to be far from the strong, decisive leader America needs.

The flip-flop attack is also designed to prevent Kerry from responding to the other key line of Bush attack - that Kerry is too liberal for mainstream America.

By criticizing Kerry for changing his position constantly, the Bush campaign hopes to stop their opponent from wriggling out of his previous liberal votes and views. Once the public is alert to the chance that Kerry will change his mind, it becomes harder for the Democrat to explain away his votes and to move to the center under Bush's fire.

Now, when Bush moves in for the kill and accuses Kerry of opposing the Defense of Marriage Act or appropriations to fund the Iraq War, the Democratic candidate will find it harder to spin his positions and to move to the middle on these issues. When he tries, voters will repeat to themselves the Ronald Reagan criticism of Jimmy Carter: "There you go again."

By showing Kerry to flip-flop, Bush sets him up for the real charges - that he is too weak and too liberal to be president.

Conventional wisdom says that this election is going to be close, a replay of 2000. It need not be so. If Bush runs aggressive national advertisements, hammering at these themes, he can put this race away by the end of the spring.

We must remember that Bush's father trailed Mike Dukakis by 17 points in the months before the conventions. Until Bush Sr. ran negative ads, it seemed that the Massachusetts governor would be Reagan's successor. Kerry's bubble may prove to be just that fragile

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.