Democratic presidential candidate Joe Lieberman (search) said that surprise Democratic front-runner Howard Dean (search) threatens to lead the party into a "political wilderness" of weakness, pessimism and defeat.

Speaking at the National Press Club (search) on Monday, Lieberman reminded Democrats of the winning ways of Bill Clinton-style centrism, and said the party must focus on strengthening America's security and economy.

"Some Democrats, on the contrary, still prefer the old, big government solutions to our problems," Lieberman said in a speech to the National Press Club. "But, my friends, with record deficits, a stalled economy and Social Security in danger, we can't afford that."

Lieberman pulled his punches when it came to naming the former Vermont governor directly, but he did make reference to him.

"I share the anger of my fellow Democrat with George Bush and the wrong direction he has taken this nation. But the answer to his outdated, extremist ideology is not to be found in the outdated extremes of our own," the Connecticut senator said.

After the speech, Lieberman denied to Fox News that he has a fixation with Dean.

"This wasn't a speech in response to Howard Dean alone. Howard Dean is obviously the surprise of the year so far," he said.

That surprise is unwelcome to Lieberman, who sees himself as the heir to Clinton centrism.

"The Democratic Party will only be able to change the leadership of this country in November of 2004 if we run a candidate — I will be specific, me — who will run from the center of American politics out," he told Fox News.

While Lieberman goes after the center to take votes from Bush, Dean says Democrats must take a stand against Bush's policies to win.

"Unlike some Democrats in Washington, Governor Dean believes that the way to beat George Bush is to stand up to him and to give people a reason to vote," said Dean spokeswoman Tricia Enright.

Lieberman said Democrats must prove they're strong on national security. Hawkish U.S. policy in Iraq is a good place to start.

"Among the nine Democrats running for president, I am the only one who supported both the Gulf War in 1991 and the war against Saddam this year," he said.

Lieberman also said Operation Iraqi Freedom is now a benchmark of Democratic credibility on national security, but also one of political consistency.

"It is an important test. Non only of whether you supported the war, but whether you stuck to your guns or became ambivalent about it when it became controversial with some parts of the Democratic constituency," he said, making a thinly veiled swipe at two of his opponents. 

Those opponents, Missouri Rep. Richard Gephardt and Massachusetts Sen. John Kerry, first supported the war but then questioned the motives, timing and planning to compete with Dean's fiery opposition. Other candidates — Sen. Bob Graham of Florida, Rep. Dennis Kucinich of Ohio, former Illinois Sen. Carol Moseley Braun and Al Sharpton — opposed the war from the start.

Lieberman also took a swipe at Gephardt's plan to provide health care for nearly all Americans and his opposition to trade treaties such as the North American Free Trade Agreement (search).

Lieberman also assailed Dean and Gephardt's calls to abolish all of the Bush tax cuts, labeling it a politically deadly call to raise middle-class taxes.

"Middle-class Americans have suffered enough under the Bush administration. We ought to be helping them, not putting more of a burden on their backs," he said.

Lieberman, who ran as Al Gore's (search) running mate in 2000, was also asked if he would choose Gore as his vice presidential nominee.

"I would guess that being vice president is something one does once in a lifetime, so I don't think that's in the cards.

Lieberman had promised not to run for president this year if Gore was in the race. He also he doesn't expect Gore to change his mind and get in now, but won't drop out if he does.

"I've crossed a bridge," he said. "I'm in this for the duration."

Fox News' Major Garrett and The Associated Press contributed to this report.