As Sen. John Kerry walked onto the Oakland stage last week, an island of yellow stood out in the sea of bodies stretching across Bigelow Boulevard. Gathered in the front ranks of his supporters was a group wearing identical T-shirts inscribed, "Firefighters for Kerry."

The University of Pittsburgh rally drew plenty of other labor contingents, as you'd expect for the presumptive Democratic presidential nominee. At a subsequent luncheon, for example, Kerry sat at the head table with Steelworkers President Leo Gerard and Bill George, the president of the state AFL-CIO.

But it's the International Association of Fire Fighters who have been with Kerry since the beginning. There was a time, in fact, when the firefighters were the lone labor fixture on Kerry's rocky campaign trail.

That persistence could bring great rewards if Kerry is able to upend President Bush come November. The IAFF would be at the top of the labor food chain, meaning a union head of less than four years, general President Harold A. Schaitberger, could end up being the most powerful labor leader in America.

And that's just fine with Schaitberger, who by age 17 was living in a firehouse and by 27 was in charge of the Virginia firefighter's union. A few years later, he joined the national union in Washington, just a few blocks from the White House.

"I want to be able to have the muscle and the influence to move our agenda forward," Schaitberger said. And that agenda, he said, is freeing up federal dollars for more equipment, more staffing and more training for the IAFF's 265,000 members nationwide. Schaitberger's wishes already are reflected in Kerry's stump speeches -- Kerry is pledging to train and hire 100,000 new firefighters across the country.

Schaitberger's rise to national prominence would seem to coincide with Kerry's reversal of fortunes, but there's more to it than that. Firefighters, in different ways, have been embraced as symbols of both presidential campaigns, thanks in no small part to Sept. 11, 2001, and the heroic, still-fresh images of firefighters charging into the smoking remnants of the World Trade Center.

That sheen, though slightly tarnished by some recent bad press involving New York City firefighters, has yet to wear off, and it translates into greater political sway for the IAFF.

"Firefighters have a very unique standing within their community," Schaitberger said last week. "They tend to be the Little League coaches, the hockey team coaches. ... When our members take a political position, [it] does resonate. John certainly understands that."

Kerry's campaign hopes the support of rugged, down-to-earth firefighters will help offset the perception that the Democrat is a stodgy, liberal blue-blood. Indeed, polls are already showing that rubbing elbows with Schaitberger and company is improving Kerry's standing among women. "There's a Zogby poll that showed women were inclined to support John Kerry when they saw him with firefighters, because they feel more secure," Schaitberger said.

Though the firefighters were Kerry's first labor ally, the Democrat doesn't hold exclusive rights to the firefighter imagery. Republicans are just as eager to embrace it -- one of the iconic images of the Bush administration was the picture of the president standing with a weary firefighter in the rubble of Ground Zero.

When the Bush re-election campaign used that image in its debut commercials, Schaitberger jumped to Kerry's aid and criticized Bush, contending that his campaign had exploited the tragedy.

Kerry leaned on the firefighters from the beginning, and the IAFF never wavered, parting with the bulk of the labor movement in making an early, critical commitment to Kerry at a time when many observers were ready to write off his chances in the Democratic nomination battle. At the Iowa Democratic Party's Jefferson-Jackson dinner on Nov. 15, firefighters -- their T-shirts were red that night -- were at the core of a loud demonstration for Kerry, a defiant reminder that the campaign still had some life in it.

Tom Vilsack, Iowa's Democratic governor, noted the firefighters' grass-roots impact on the Kerry campaign in the days before the caucuses, pointing out that while Iowa has relatively few full-time professional firefighters represented by the IAFF, the state is filled with volunteer firefighters with common interests. Many of them showed up for the Massachusetts senator on caucus night -- the victory that created the momentum for Kerry's march to almost certain nomination.

The IAFF support for Kerry is rooted in opposition to President Bush and the belief that Kerry was the Democrat best positioned to defeat him. (The IAFF also supported former Vice President Al Gore in the 2000 election.) Schaitberger, who appeared on stage with Kerry when he claimed his Iowa prize, has criticized Bush for failing to provide adequate federal funding for fire companies.

"[The administration] opposes your right to bargain collectively," Schaitberger wrote to his membership last year.

"It supports privatizing fire and EMS services."

He pointed out that Kerry, by contrast, was a co-sponsor of the Father Mychal Judge Act, a proposal named for the New York Fire Department chaplain killed in the Sept. 11 bombing of the World Trade Center. That measure is the basis of Kerry's promise to hire 100,000 new firefighters, modeled after a Clinton administration initiative that provided federal funding to hire local police officers.

Meanwhile, at Pitt and elsewhere, Kerry has been telling crowds that "George Bush opens fire stations in Iraq and forces fire stations to shut in America. ... There are firefighters here and they know the truth."

While Schaitberger has earned major political chits with the Kerry campaign, he still may have a tough sell with many of his members. Forty-four percent of the IAFF members are registered Republicans, and in fact the GOP proportion is greater than the Democrats', who make up 40 percent of the union. The rest are independent.

Schaitberger said that whoever the IAFF endorses can expect between 60 percent and 65 percent of the union vote, regardless of the candidate's party affiliation. Union officials also point out that despite the back-to-back Gore and Kerry endorsements, it has a record of bipartisanship. At the congressional level, Schaitberger said in another letter, it supports more Republicans than any other union.

Jeff Zack, a member of the IAFF staff, said that the union's political action committee made more than 30 percent of its contribution to Republican candidates. While opposing Bush at the presidential level, he noted, the group had endorsed his brother, Florida Gov. Jeb Bush, for re-election.

Competing for the firefighters' constituency, the Bush-Cheney campaign formed a group last week that it called The First Responders Leadership Team, comprising firefighters and other emergency workers. From Pennsylvania, the group includes Tom O'Drain, the president of Philadelphia Firefighters Local 22.

Schaitberger likes the idea that his firefighters are now the prettiest girl at the ball, and everybody wants to put them on their dance cards. "They've seen that we can make a difference," he said. "When things were bad for John, we didn't blink. We didn't abandon our candidate. That brings with it some positives for our union. There's nothing like winning."