On what was, undoubtedly, the most important day so far for his campaign for the presidency, John Edwards arranged to take time away from shaking hands with actual voters in the critical state of South Carolina to meet with a group of people who could not vote in that state, nor in any of the half dozen others that held primaries and caucuses on Tuesday.

Yet, the people with whom Edwards agreed to meet could hold the power to decide whether the North Carolina senator really will be able to mount a serious challenge to frontrunner John Kerry in the race for the Democratic presidential nomination. They were the leaders of several of the industrial unions that backed the failed candidacy of Dick Gephardt. Though they could not deliver for the former House Minority Leader, who ran a weak fourth in the January 19 Iowa caucuses and then withdrew, the more than 20 unions that backed Gephardt are finding that the doors of the remaining Democratic contenders remain very much open to them.

For Edwards, who won South Carolina’s primary and posted solid second-place finishes in several of the other states that voted Tuesday, support from just a few of those unions — particularly the 1.4-million member International Brotherhood of Teamsters and the 700,000-member United Steelworkers of America union — could provide him with the infrastructure he needs to compete in northern industrial states such as Michigan, Wisconsin, Ohio and Illinois. It is in these states that Edwards will in coming weeks be under pressure to nationalize what some analysts still dismiss as a southern regional campaign, and union backing could make all the difference.

“With the Teamsters and a few other unions pulling for him, Edwards might be able to secure some upsets and really emerge as the alternative to Kerry,” said a veteran labor leader from the upper Midwest, who backs none of the candidates at this point. “But, without them, I don’t see how Edwards can build the organization he needs to take this thing national.”

The industrial unions like Edwards. To their view, he’s got a significantly better record on the international trade issues that are so vital to union members who have seen hundreds of thousands of jobs eliminated, as a result of the North American Free Trade Agreement and Permanent Most-Favored Nation Trading Status with China. Edwards has never been so passionate a critic of the corporate free-trade agenda as Gephardt, who helped organize Congressional opposition to NAFTA and the granting of “Fast Track” authority to negotiate a sweeping Free Trade Area of the Americas agreement, or Congressional Progressive Caucus co-chair Dennis Kucinich, D-Ohio. But, as far as labor is concerned, Edwards has a far better record than Kerry, whose support for free trade agreements has been almost as consistent as that of Connecticut Senator Joe Lieberman, the corporate-friendly Democrat whose miserable showings in Tuesday’s primaries and caucuses ended his presidential run.

Already, the Steelworkers union district that includes Michigan and Wisconsin has endorsed Edwards.

But most unions are holding off for now. The union leaders who met with the North Carolina senator Tuesday are expected to meet Thursday with Kerry, who has won seven of the nine primaries and caucuses held so far.

With Kerry emerging as the man to beat, unions that had backed Gephardt are cautious about going against him. They might prefer Edwards, but they will need a solid rational for doing so. There is real fear on the part of many labor leaders about backing two losers in the same nomination fight.

Some unions have already jumped to Kerry. Even before his breakthrough wins in Iowa and New Hampshire, the Massachusetts senator always had the backing of the 260,000-member International Fire Fighters Association and the 50,000-member Utility Workers Union of the America. And as his campaign has picked up steam, he has received endorsements from the 700,000-member Communications Workers of America union, the 150,000-member Sheet Metal Workers International Association and the National Treasury Employees Union, which represents 150,000 workers in 29 government agencies. He has also gained the backing of the 27,000-member United Farm Workers union, which maintains influence beyond its numbers in Latino communities. And he is expected to secure the support of the 1.2-million member American Federation of Teachers union before the end of the week.

Kerry has also earned backing from a number of powerful union groupings in Michigan, where caucuses will be held Saturday. The 157,000-member Michigan Education Association is for him, as are United Auto Workers union Region 1D, the Michigan Regional Council of Carpenters and the West Michigan Building Trades Association.

Former Vermont Governor Howard Dean, who hopes to renew his campaign with a strong showing in Michigan, says, “The Michigan Education Association has endorsed Senator Kerry, but I think I’ll get the vast majority of teachers’ votes.”

Dean had better hope he’s right. He needs strong showings in Michigan and Washington state, which also holds caucuses on Saturday, as well as Wisconsin, which will hold what is shaping up as a critical primary on February 17. Dean’s still has the backing of two of the largest unions in the AFL-CIO, the Service Employees International Union, the American Federation of State, County and Municipal Employees. But the former frontrunner is under pressure to deliver some wins soon. Both unions have spent in the range of $1 million to aid Dean who, so far, has been beaten in nine primaries and caucuses.

Dean will be called to explain his strategy for renewing his campaign in meetings later this week with leaders of AFSCME and SEIU, as well as another union that endorsed him when his campaign was on the rise, the International Union of Painters and Allied Trades. “Obviously, people are nervous. Obviously, they’d rather be in a different situation strategically,” says Bob Muehlenkamp, the former Teamsters union organizing director who has been helping Dean line up labor support. “Obviously, people have doubts and hesitations when you’re not winning elections and getting votes.”

SEIU President Andy Stern says his union is committed to back Dean through Wisconsin’s February 17 primary. “As Dr. Dean has said, he wants to win, he’s not there to be a protest candidate,” says Stern. “At some point he’s going to have to decide if he’s getting enough delegates and does he have the strategy to win.”