On the labor front, Edwards has the United Steelworkers and the United Mine Workers unions, and statewide endorsements from the Service Employees International Union in Iowa and 11 other states. Clinton counts the government employees union AFSCME, the American Federation of Teachers and at least a half-dozen other national unions in her corner.
Official union support translates into volunteers on the ground and millions in spending. AFSCME, for example, has financed an automated phone call critical of Obama's health care proposals.
Obama campaign manager David Plouffe took aim in a weekend memo at what he called "underhanded" spending by outside groups, mostly unions, to the tune of nearly $5 million.
AFSCME President Gerald McEntee wrote at The Huffington Post website that unions are not special interests — "we fight for the general interest" — and said AFSCME had given money and volunteers to past Obama campaigns.
The spat underscores the distinction the Obama campaign makes between union leaders and their rank-and-file. "We have support among union members who respond to Obama's message," Obama strategist David Axelrod says.