Four of Change to Win's unions had already endorsed Obama, with the Teamsters endorsing Obama on Wednesday. UNITE HERE, the Service Employee International Union and the United Food and Commercial Workers also have endorsed Obama.
The Change to Win endorsement gives Obama a boost in the upcoming March 4 primaries in Texas and Ohio, as well as in Pennsylvania on April 22. There were 830,000 union workers in Pennsylvania and 730,000 in Ohio in 2007, according to the Bureau of Labor Statistics, some of the largest numbers of unionized workers in the nation.
It was not immediately known what the endorsement means for the United Farm Workers, who endorsed Obama's opponent, Sen. Hillary Rodham Clinton. It is also unclear what it means for the federation's two uncommitted unions, the Laborers' International Union and the United Brotherhood of Carpenters and Joiners. The Carpenters and Joiners union had originally endorsed John Edwards, who has since dropped out of the race.
The unions in the Change to Win federation broke from the AFL-CIO in 2005 over internal disagreements on how best to build organized labor's membership and political clout.
The AFL-CIO has not endorsed any candidate in the Democratic primary, although it has allowed its 56-member unions to make individual endorsements. The AFL-CIO's executive council will meet in San Diego March 3-5, and a decision could be announced.