Sen. Hillary Clinton will be endorsed next week by the American Federation of State, County and Municipal Employees Union, Newsweek's Howard Fineman reports. The group boasts 30,000 members in Iowa, and large contingents in other early states.

That's many more than the 2000 members SEIU boasts in Iowa -- the Service Employees in several states, including Iowa, are backing former Sen. John Edwards -- but SEIU can also import members from California, which is also backing Edwards. The Golden State's SEIU contingent is more than 650,000 members strong.

AFSCME, Fineman notes, came out strong for Bill Clinton in 1992, well before he was the front-runner. Fineman reports the former president called union chief Gerald McEntee on behalf of his wife. AFSCME joins the American Federation of Teachers and the Machinists union in Clinton's corner.

Edwards has attracted the support of the Steelworkers and Miners unions as well as SEIU statewide chapters across the country. The national SEIU couldn't reach an agreement on a single candidate to endorse after locals in New York and Illinois, home territory of Sen. Barack Obama, objected to a national endorsement. Obama has picked up support from state SEIU councils in his home state and in Indiana.