When unions speak, Democratic political candidates listen closely.

That would explain the attendance of all nine Democratic presidential hopefuls at a candidate's forum sponsored by the AFL-CIO (search) in Chicago last month.

Candidates are eager to get the support of labor unions for one reason — union members are going to the polls in record numbers.

"The union member and union household votes were 26 percent of the people who voted in the 2002 election. We brought that up from 23 percent for the previous election and 19 percent from the election before that," said AFL-CIO Executive Vice President Linda Chavez Thompson (search).

"Over a period of the last six years, we have brought the union vote up considerably higher than any other time in the history of the labor movement," said Chavez, who added that her organization wants to increase union voter registration by 10 percent before the next election.

But union members provide more than just votes. They are boots on the ground in the form of volunteers and millions of dollars in union campaign contributions. Chavez said the unions are likely to pump $45 million into next year's election.

So far, Missouri Rep. Dick Gephardt (search), who has courted the unions for three decades, already has the backing of at least 12 labor groups, including the Steel Workers Union (search) and the Teamsters.

"[Teamsters President] Jim Hoffa said we'll fight for our families. You bet we'll fight for our families, and we'll fight for health insurance for our families. And when I'm president we will get this done," Gephardt recently promised laborers.

"Dick Gephardt is clearly the candidate of labor and for the simple reason that he's been there. His economic policies are policies that the labor movement supports. They are pro-worker, pro-employee, his trade policies are policies that are geared to protecting jobs in the United States," said Greg Tarpinian, president of the Labor Research Association.

The AFL-CIO has not completed the process of choosing the candidate it will endorse, but is expected to vote on the matter in October. The winner would need to receive support from unions representing two-thirds of the members in order to emerge with the AFL-CIO's backing.

So far, Gephardt appears to be the favorite son. Union leaders say they believe it is important to get behind their candidate early in the process.

"Labor's biggest impact can be in the primaries when it can take a candidate that may be neck-in-neck or may be marginal, and it can push him to the top of the heap," Tarpinian said. "Given the cast of characters in the Democratic Party right now, the unions feel that if they get in now with Gephardt, Gephardt could indeed be the nominee."

But make no bones about it, even if Gephardt for some reason does not emerge as the winner of the primary fight ahead, unions still plan to rally around the Democratic nominee for president.

"Whether it's Gephardt, Kerry, Graham, Lieberman. Anybody. If any union endorses any of them and their candidate does not make it out of the primaries, everyone will be together on whoever the candidate is against George Bush," Chavez said.

Unions have traditionally aligned themselves with Democrats in part because the Republican Party has long been aligned with business interests. Republicans often like to think of themselves as "free-traders" and unions do not generally like the trade agreements supported by the GOP.

And that leaves them nowhere to go when their guy turns away from them. Unions continued to stand by Bill Clinton even when he supported the North American Free Trade Agreement (search). President Bush, however, should probably not hold out hope for organized union support.

"He clearly has given us the sign that he is not a friend of organized labor," Chavez said.

Few Republicans have found favor or financial support from the unions. Rep. Peter Hoekstra, who has represented the 2nd District of Michigan since 1992, is an exception. He has earned some support from labor for his stance against international trade agreements and his leading the congressional investigation that ousted corrupt former Teamsters President Ron Carey. He said Republicans need more dialogue with union officials.

"What they need to do is they have to recognize there are a number of issues that they will be in agreement with organized labor ... and say ... you may not have endorsed me or you may have campaigned against me in the last election and you may do the same in this election, but let's set that aside," Hoekstra said.

The advice may come a little too late during this election cycle, in which unions seem certain to be universally aligned against Bush. To inoculate himself from the effects of the unions, Bush is already out raising a massive campaign war chest.

Fox News' Brian Wilson contributed to this report.