CHARLESTON, W.Va. -- The West Virginia AFL-CIO is supporting House Speaker Rick Thompson in his bid for governor.

The union announced its endorsement of the Wayne County Democrat on Saturday. Thompson also has been endorsed by the West Virginia Education Association and the West Virginia Federation of Teachers.

The state AFL-CIO's political education committee interviewed Democratic candidates, who also filled out questionnaires. The endorsement required a two-thirds majority of votes among members of the committee.

West Virginia AFL-CIO President Kenny Perdue said the choice was difficult because the union felt there are several strong candidates in the race.

Among other issues, the union asked candidates about where they stand on collective bargaining, mine safety, education, Marcellus Shale development, privatization of state agencies, prevailing wage and whether they support allowing public employees to run for office, Perdue said.

The AFL-CIO also cited Thompson's pro-labor voting record in the state Legislature when endorsing him.

Other Democrats who are running in the special gubernatorial election are Sen. Jeff Kessler; Kanawha County resident Arne Moltis; state Treasurer John Perdue; Secretary of State Natalie Tennant; and Sen. Earl Ray Tomblin. The primary election is scheduled for May 14.