California Lt. Gov. John Garamendi (D) is expected to announce Wednesday that he is suspending his 2010 campaign for governor and will instead run for the seat of Rep. Ellen Tauscher (D-Calif.), assuming she is confirmed to be assistant secretary of State.

Garamendi’s announcement will transform the race for Tauscher’s East Bay seat, which until now has been dominated by state Sen. Mark DeSaulnier (D).

Because Tauscher hasn’t been confirmed for the State Department post, she hasn’t resigned her seat, and no timetable has been set for the special election.

Garamendi had been running for governor, but most recent polls had shown him running fourth in a hypothetical Democratic primary. He has begun talking openly of making a Congressional bid in the past two weeks.

Garamendi is scheduled to visit employment centers in Concord and Fairfield on Wednesday as he launches his Congressional campaign.

DeSaulnier has already been endorsed by Tauscher and Rep. George Miller (D), who represents an adjoining East Bay district. He has also picked up key labor endorsements, including the backing of the Contra Costa County Central Labor Council.

But Garamendi’s entry into the race could provide a dilemma for many Democratic activists. What’s more, the presence of two well-known male candidates in the race increases the possibility that state Assemblywoman Joan Buchanan (D), who is also pondering a bid in the special Congressional election, enters the fray.