Labor Day marks the unofficial kick-off of the 2004 presidential election campaign. Most of the nine candidates vying for the Democratic nomination spent Monday marching in parades or participating in other events to show their support for workers on this national holiday.

Missouri Rep. Dick Gephardt (search), who spent the day feasting with union members in New Hampshire, desperately wants the AFL-CIO (search) endorsement for the 2004 Democratic nomination for president. But despite nearly three decades of advancing union causes, he said the prize is still not easy to land.

"Well, to get it, you have got to get two-thirds of the union members — or the unions that have two-thirds of the members — for you, and endorsing you by sometime this fall. That's very hard to do. But I have a chance to do it, and I am working hard to do it, and I am doing it bottom up, not top down. I am doing it one union at a time. I am going door to door," Gephardt said in a Fox News interview for Labor Day.

Gephardt's winning strategy depends on clinching the leadoff test in Iowa, where nearly a third of the first-in-the-nation caucus attendees are union members. He frequently points out that he has stood with labor against various international trade deals that his top rivals supported.

"Others in this race were voting for those treaties without proper labor and environmental provisions. And now they are saying, 'I would never sign a treaty that didn't have these provisions,'" Gephardt said. "You have got to look at people's record and you have got to look at who was there when these issues were on the line."

With or without labor's help, in the lead-off states of Iowa and New Hampshire and around the country, the headlines, the fund-raising and more and more of the polls are dominated by one man: former Vermont Gov. Howard Dean (search).

Dean is attracting remarkably enthusiastic crowds, often in the thousands, and expanded his advertising blitz this past weekend to six more states. Once an unknown running a come-from-behind strategy, his attacks on his own party, his rivals, the Bush administration and Washington in general have turned him into a front-runner.

"Well, I am definitely an outsider. I mean, if you look at what's happening in this race, people are saying, 'Look, the Washington candidates had their chance and this isn't going to work,'" he said.

Dean is leading the polls in Iowa against Gephardt and in New Hampshire against Massachusetts Sen. John Kerry (search). His surge has caused his rivals to retool their messages and strategy as the torrent of debates, campaign rallies, policy speeches and attack ads get started this fall.

Counting on a strong showing in New Hampshire is Kerry, the four-term U.S. senator and the only Vietnam veteran in the race. Kerry constantly suggests that only he has the experience to lead the nation in a post-Sept. 11, 2001, world.

"I will not just bring to that profound responsibility the perspective of sitting in a situation room. I will bring the perspective of someone who's fought on the front lines," he recently told a convention of Veterans of Foreign Wars.

Despite Kerry's occasional swipes at his rivals, for the most part he tries to ignore the rest of the field and cast himself as the only contender with the stature to compete against President Bush on security matters, one of Bush's perceived strengths.

"I think America can be safer than George Bush is making us today. And it requires a president who has experience and a vision that builds relationships with other countries in the world," he said.

While Kerry casts himself as the front-runner, in the national polls, Connecticut Sen. Joe Lieberman (search), who ran as former Vice President Al Gore's running mate in 2000, is the real leader.

Lieberman, a centrist and staunch backer of the war against Iraq, argues that any sign of dovishness, weakness on national security or old-style liberalism will render Democrats unable to unseat Bush.

"What the candidates did about the war against [deposed Iraqi leader] Saddam [Hussein] is a test for what kind of commander-in-chief they would be. And I don't believe the American people are going to elect a president in 2004, post-Sept. 11, in an unsettled world, a candidate who has been opposed to the use of American military power against a brutal dictator like Saddam Hussein, or seems ambivalent about it — supported the war but then was looking for a lot of ways to criticize it," Lieberman said.

In the highly influential lead off states of New Hampshire and Iowa, where Dean is white-hot right now, liberal activists have turned up their noses at Lieberman's centrism. He has had to deny rumors about withdrawing from the race early, and has lowered expectations by saying he will come back in the South and West during the highly compressed, eight-week primary season next spring.

"We have a lot of other states that are going to hold their primaries during February, and I think it is there that the nomination will really be decided. This is a national nomination and people all around America, I think, will have an opportunity in the Democratic primaries to say who they want. And I am confident when that happens that I will emerge the nominee," he said.

Also struggling in the polls is North Carolina Sen. John Edwards (search). Being a Southerner helps in presidential politics, but Edwards, a youngish-looking, 50-year-old first-term senator has so far been unable to catch fire. He justifies his slow start by calling it his strategy.

"We are actually doing exactly what we planned to be doing. We are exactly on track of what we planned. I spent most of the first six months of this year, 2003, making sure we had resources to run a serious national campaign so the vast majority of my time was spent raising money ... now we have changed," he said.

Changed so far has been Edwards' visibility. He is now airing ads in three states and has been touring the nation by bus. Though he has doubled his showing in the polls in recent weeks, he is still in the low single digits hovering around fifth place.

The other Southerner also trailing far back in the polls is Florida Sen. Bob Graham. He is strapped for cash and struggling for attention, but because he is from Florida, the state that decided the 2000 race and could again be crucial to the 2004 contest, he is seen as a potentially valuable running mate.

While there are three other hopefuls — Ohio Rep. Dennis Kucinich (search), civil rights activist Al Sharpton and former U.S. Sen. Carol Moseley Braun (search) — they are not seen as competitive contenders. But all of them for now have one target separate, of course, from the Republican president.

"I think they will all pound me. You know, these guys want to be president. So do I. I am now ahead of them. They're going to come after me with everything they've got. I understand that," said Dean.

Fox News' Carl Cameron contributed to this report.