Democrat Barack Obama is telling union activists he would walk a picket line as president if organized labor helps elect him in 2008.
The Illinois senator also criticized President Bush's policies toward working people.
'We are facing a Washington that has thrown open its doors to the most anti-union, anti-worker forces we've seen in generations," Obama said in remarks prepared for delivery Saturday night. "What we need to make real today is the idea that in this country we value the labor of every American."
Obama was scheduled to speak to Iowa's largest union representing more than 20,000 state workers.
Four other Democratic presidential candidates have courted activists at the annual convention of Council 61 of the American Federation of State, County and Municipal Employees.
Like his rivals, the Illinois senator challenged Bush's labor policies and said he was committed to union causes.
"I stood on the picket line and marched with workers at the Congress Hotel in Chicago last week," Obama said. "I had marched with them four years earlier and I told them when I left that if they were still fighting four years from now, I'd be back on that picket line as president of the United States."
In his prepared remarks, Obama cited his years as a community organizer in Chicago. Because of that experience, Obama said he has closer ties to people who are struggling. He asked union activists to keep that in mind in choosing a candidate to support in January's Iowa caucuses, which begin the presidential nominating process.
"So I want you to remember one thing, because you'll hear from a lot of candidates between now and January," Obama said. "When I talk about hope, when I talk about change, when I talk about holding America up to its ideals of opportunity and equality, this isn't just the rhetoric of a campaign for me, it's been the cause of a life - a cause I will work for and fight for every day as your president."
Obama portrayed himself as a political outsider, saying it takes a new figure in Washington to break the gridlock.
"We've heard promises and slogans about change before," said Obama. "The road to Washington is often paved with good intentions, but it always ends in the same divisive, polarizing politics that's blocked real progress for so many years."
The union plays an important role in Iowa Democratic politics. In addition to campaign money, the union's endorsement brings into play a legion of talented organizers throughout the state.
Former Sen. John Edwards, Sens. Hillary Rodham Clinton and Chris Dodd and New Mexico Gov. Bill Richardson also spoke to the union leaders.