"This endorsement reflects Senator Edwards' lifelong commitment to standing up for working Americans like the people he grew up with," said the senior campaign official, who requested anonymity because he was speaking about the endorsement before its official release.
He told The Associated Press that a "number of other state councils" of the SEIU will announce their support for the former North Carolina senator at an event in Iowa City on Monday evening, but he wouldn't confirm how many.
Edwards was stung last week by the national SEIU when leaders said it would not endorse a candidate for the primary elections, letting its members make their decisions on a state-by-state basis.
Edwards had worked hard to win the seal of approval from the union, which claims to be the fastest growing in North America, boasting 1.9 million members in the U.S., Canada and Puerto Rico.
The 2004 Democratic vice presidential nominee has spent considerable time the past couple of years walking picket lines, speaking out for workers' rights and seeking labor support. He has already earned endorsements from the United Steelworkers, United Mine Workers of America, the United Brotherhood of Carpenters and Joiners of America and the Transport Workers Union of America.
Cathy Glasson, a registered nurse and president of SEIU Local 199, said Edwards' health care plan was pivotal to earning the support in Iowa.
"We are uniquely positioned to see and hear the candidates and members are well informed on the issues important to working families," she said in a statement. "John Edwards earned our support by taking a strong stand on health care and because he offers our members the greatest hope for restoring the American Dream."