SAN FRANCISCO -- Presumptive Democratic presidential nominee Barack Obama made a brief appearance via satellite Thursday before thousands of union members at a convention in San Francisco.

Obama's address came about an hour after his former rival, U.S. Sen. Hillary Clinton, spoke to the union members live and urged them to support the Illinois senator in November.

Henry Bayer, an international vice president of the American Federation of State, County and Municipal Employees, introduced Obama at the union's convention at Moscone Center, saying, "He has stood with AFSCME and the labor movement time and time again."

Speaking from Cedar Rapids, Iowa, Obama thanked the union for endorsing his presidential bid and highlighted his experience working with the union, sticking to his message that he represents change.

"Change is a president who walked with you on the picket line, who doesn't choke when he says the word 'union'," Obama said.

He said he will work against privatization and that his proposed economic stimulus package is not designed to jump-start the economy but rather to help families and individuals afford food and other necessities.

Obama recognized presumptive Republican presidential nominee John McCain's public service but likened his policy choices to that of President George W. Bush.

He thanked Clinton, saying running against her made him a better candidate.

Clinton spoke about an hour before Obama, and took the stage to the sounds of the song "We Are Family" and cheers from union members throughout the conference room.

The New York senator applauded their public service and said she will work with them to ensure a Democratic victory in the November election.

"We have to work hard and it won't be easy," Clinton said.

She thanked union members for their support during her presidential campaign, which she called "a remarkable journey," and encouraged the union to support Obama in November.

"His life exemplifies the American dream," she said.