Union leaders in the AFL-CIO are considering supporting challengers to centrist Democrats in this year's mid-term elections.

Disappointed with Blue Dogs who helped foil the unions' hoped-for agenda in President Obama's first year, leaders of unions such as the United Steelworkers and AFSCME are considering supporting more union-friendly and more progressive candidates for the 2010 mid-term elections.

According to James A. Barnes in the National Journal, AFL-CIO members brought up the names of three Democratic senators some among them would like to see defeated: Blanche Lincoln of Arkansas, Ben Nelson of Nebraska, and Joe Lieberman, the Connecticut independent who caucuses with the Democrats and who is credited -- or faulted -- with scuttling the public option in the Senate.

Of those three, only Lincoln is up for re-election in 2010.

If the unions go ahead with the idea, they would mirror in the Democratic Party what appears to be happening with the Tea Party movement and the Republican Party. Members of the Tea Party movement are mobilizing to support like-minded candidates in the GOP primaries, in an attempt to force the Republican Party further to the right.

It's a strategy that some political analysts see as risky because it could result in primaries being won by candidates who are popular with the party base, but not with moderates, making it difficult to win the general election.

One example would be the special election in New York's 23rd congressional district last year, where Tea Partiers supported a third-party conservative candidate, Doug Hoffman, over the moderate GOP candidate Dede Scozzafava. With the conservative vote split between two candidates, Scozzafava withdrew and Democrat Bill Owens won.

But for union leaders, it's a matter of principle.

"A number of us expressed our dismay with some of the senators from the Democratic Party who have held up and helped delay not only the passage of the health care bill but all kinds of other things that would help middle-class workers," United Steelworkers President Leo W. Gerard told the National Journal. "I, for one, am not prepared to work for Democrats who are going to help play that Republican game of just trying to stop legislation."

America's unions have been among the most vocal supporters of health care reform, the public option in particular. AFL-CIO leader Richard Trumka told Congress in September that his union would not support health care reform if it didn't include a public option. True to its word, the labor umbrella group, which represents some 11 million workers, came out against the Senate health bill, which has no public option.

National Journal's Barnes reports that the idea to challenge centrist Dems came up at a January 25 meeting of the AFL-CIO's executive committee, and "some people clearly supported" the move, said Gerald McEntee, president of AFSCME. The Service Employees International Union, which is not part of the AFL-CIO, is also considering challenging centrist Dems, Barnes reports.

If the unions decide to go ahead with the idea, blogger TomP at DailyKos suggests Bill Halter, the lieutenant-governor of Arkansas, as a likely challenger to Sen. Blanche Lincoln, noting that the SEIU helped Halter retire his debt from his run for lieutenant-governor.