Seizing on a fresh report about the financing of critical ads, Democrat Howard Dean (search) assailed front-runner John Kerry (search) on Wednesday for being part of "the corrupt political culture in Washington."

Struggling to right his winless campaign, Dean focused on the disclosure that former Sen. Bob Torricelli (search), who now raises money for Kerry, donated $50,000 to an independent group that ran controversial ads in three early-voting states.

One commercial showed terrorist leader Usama bin Laden (search) as the group sought to raise doubts about Dean's national security credentials. Other spots focused on Dean's previous support of NAFTA, his past comments supporting slowing the growth of Medicare and his eight endorsements by the National Rifle Association while he was governor of Vermont.

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"The link is unassailable," Dean said, describing Torricelli as "ethically challenged." Amid an ethics scandal, Torricelli quit his 2002 re-election bid five weeks before Election Day.

Torricelli declined to comment.

Nearly all the donors to Americans for Jobs, Healthcare and Progressive Values were backers of Dean rival Dick Gephardt, the Missouri congressman who staked his candidacy on Iowa and was in a head-to-head battle with Dean there weeks ago.

"What we now see is John Kerry is part of the corrupt political culture in Washington," Dean told The Associated Press in an interview. "That's exactly what I'm asking Wisconsin voters to stand up against."

On the same day he criticized Kerry's links to the ads, Dean said John Edwards would be a better candidate against President Bush in the general election.

"I think that Senator Kerry has an enormous advantage. My fear is that he (Kerry) won't be the strongest Democratic candidate," Dean told CBS News in an interview to air Wednesday night. "I've actually said on the record that I thought Senator Edwards would be a stronger candidate against George W. Bush than John Kerry because when Senator Kerry's record is examined by the public at a more leisurely time when we're not having primaries every week he's going to turn out to be just like George Bush."

Asked about Dean's comment, Edwards told reporters: "I agree with that. I think that he is a very wise man. ... The truth is that this campaign to bring about change is working with independents and voters that we will have to get in order to win the general election."

Dean has been fighting to latch onto the progressive political tradition in Wisconsin while campaigning for the state's Tuesday primary. He has said the primary is key to the viability of his campaign and that Kerry, the winner of 12 of 14 delegate elections, has yet to be adequately vetted.

In a news conference Wednesday where he accepted the endorsement of a Milwaukee teachers' union, Dean did not temper his criticism of Kerry even though he has said he would do nothing to harm the potential Democratic nominee.

"I intend to support the Democratic nominee under any circumstances," Dean said. "I'm just deeply disappointed that once again we may have to settle for the lesser of two evils."

Dean was the front-runner in the race for the nomination when he was sidelined, in part, by the group's ads. He said the disclosures proved his point that "Washington insiders" were united in their effort to defeat him, an outsider.

"I ran because Democrats wouldn't differentiate themselves from the Republicans," he said. "It now turns out they're more like each other than I thought."

David Jones, the group's treasurer and a Democratic fund-raising consultant, said its goal had been to point out Dean's stands on issues and that he had no experience in foreign policy, which Jones said would be the top issue of the campaign.

"Our goals were accomplished, clearly," Jones said. "What he is doing now is the last gasp of a dying campaign."

Dean has spent every day since Sunday campaigning in Wisconsin. He expects to be here through the primary, with quick trips to Vermont on Wednesday and Saturday to attend his 17-year-old son's last hockey games of his high school career, and at least one fund-raising trip to neighboring Minnesota.