GRAND JUNCTION, Colo. | Andrew Carillo and Melissa McCollister cheered loudly from near the back row of the Central High School gymnasium as President Obama stepped on stage to make his pitch for health care reform.
The two organizers for the United Food and Commercial Workers (UFCW) Local 7 proudly wore their union T-shirts, and boisterously supported the president because of what they think his initiative will do for the 25,000 grocery stockers, meatpackers and warehouse workers that they represent.
"We have to negotiate for health care every time a contract comes up," said Mr. Carillo, 24, a union employee. "Year after year, it just gets more and more expensive."
Members of the nation's labor unions have made up a hefty segment of the audiences that flocked to town halls Mr. Obama held in the past week, and they have played an even larger role in a nationwide campaign for an insurance overhaul. Financially, and with boots on the ground, unions have become the backbone of the president's effort.
Last week, the Service Employees International Union (SEIU) was part of a group, largely funded by the pharmaceutical industry's lobby, that launched $12 million in television ads to support the president's health care push, and the coalition Americans for Stable Quality Care could spend tens of millions of dollars more this fall.
The AFL-CIO, the American Federation of Teachers and the American Federation of State, County and Municipal Employees are among the partners in another group, Health Care for America Now, which has committed millions more dollars to advertising that is running now in a half-dozen states.
But money is only part of the equation; the most potent contribution from labor has been its people. Last month, opponents of the president's health care efforts began protesting, at times vociferously, as members of Congress convened town-hall meetings in their districts.
The Obama administration decried the opposition movement as a cynical, fake grass-roots campaign manufactured by the insurance industry to undermine his effort. To respond meant galvanizing a movement of his own. That began to take shape, at least visibly, when AFL-CIO President John J. Sweeney sent an Aug. 6 memo to union officers across the country to mobilize.
"The question for us is: will we let them make health care 'Obama's Waterloo' or will we make it the next big step in our march to Turn Around America?" Mr. Sweeney wrote. "August will tell!"
Mr. Sweeney's memo called on members to mobilize during Congress' August recess.
"We wanted them to show up at town halls both for members of Congress who are on the fence, but also for members who are supportive of reform," AFL-CIO spokeswoman Amaya Tune said. "We wanted them at the district offices, meeting with members of Congress and communicating with other union members to tell them what's involved in health care reform."
The union organization also began a rapid-response program for town-hall meetings, sending out e-mail alerts to members who live in ZIP codes near where town halls are planned, urging them to attend. Phone banks were set up for members to put out calls explaining why they think the president's initiative is needed.
Since the union pushback began more than a week ago, there have been scuffles between activists on both sides of the issue outside at least two town-hall meetings, in St. Louis and in Tampa, Fla. In the St. Louis meeting, widely circulated video footage shows conservative counterprotester Kenneth Gladney lying on the street surrounded by SEIU members. He later told the St. Louis Post-Dispatch that he sought hospital treatment.
Labor has much at stake in the health care debate unfolding in Washington, said Richard Berman, a food-industry lobbyist who has battled the unions on Capitol Hill.
"SEIU is leading the charge for health care because they stand to make major gains in unionizing the entire system," Mr. Berman said. "They might try to inject some pro-union requirements into the bill."
Unions may seek gains in other areas, too, including the potential to loosen labor department regulations, receive pension assistance and secure another increase in the minimum wage.
But perhaps the most powerful incentive for members to get out to town-hall events has been the desire to see political success for Mr. Obama, a candidate for whom they campaigned vigorously to elect last fall.
Their mobilization behind the health care plan has been most visible at the president's town-hall events.
While the administration has billed as organic the response to the president's appearances in New Hampshire, Montana and Colorado, union members interviewed at the events described an extensive effort to recruit large numbers of the president's supporters to fill the audiences, and to line up opposite protesters attracting attention outside.
In New Hampshire, the air traffic controllers union handed out tickets to its members. The Massachusetts Nurses Association had members cheering the president outside the event with a banner unfurled.
SEIU's Mark McCullough said his union had nothing to do with passing out tickets to Mr. Obama's town-hall events. But he said the organization pushed hard "to have members at the event itself and around to show their support for health care reform."
In Grand Junction, three of Mr. Carillo's union colleagues had seats on stage behind the president, while hundreds more rallied outside the high school, shuttled to the event on two large buses that the UFCW had hired. Also on stage were leaders from the International Brotherhood of Electrical Workers (IBEW). In the audience were members of the Colorado Education Association, which represents the state's schoolteachers.
That was how Jim Smyth, 48, obtained his ticket to the event, even though he said he has been too busy monitoring the start of the school year to pay close attention to the raging health care debate.
"Our biggest concern is to make sure we don't lose any of the benefits we have now, if there is a change," Mr. Smyth said.
Troy Goodson, 55, and Larry Beard, 57, are electricians in Grand Junction who came to the Obama event to show the support of the IBEW Local 969. Both said they know how much is at stake in the health care debate.
Mr. Goodson said he has triplets at home, and that the delivery costs alone would have left him underwater financially had he lacked adequate insurance. He said he's glad to see labor unions out in force, pushing for the president's plan.
"The big corporations and the insurance industry, they're lobbying 24/7," Mr. Goodson said. "Someone has to fight against that."