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Washington State Senate approves gay marriage measure

Elaine Thompson / AP

Members of the gallery look down and applaud as the Washington state Senate passes a bill that would legalize same-sex marriage Wednesday evening.

Elaine Thompson / AP

Gov. Chris Gregoire motions Sen. Ed Murray over to embrace him after the Washington state Senate voted for a proposal to legalize same-sex marriage Wednesday evening.

Elaine Thompson / AP

Rep. Laurie Jinkins, right, D-Tacoma, waves with constituent Marcy Kulland from one Senate gallery across to the other Wednesday, Feb. 1, 2012, in Olympia, Wash.

The Washington state Senate has passed a bill that would legalize same-sex marriage, a step seen by proponents as a critical hurdle for legislative approval, even as the threat of a ballot challenge looms.

The measure was passed on a 28-21 vote. Four Republicans crossed party lines and voted with majority Democrats for the measure. Three Democrats voted against it.  The measure now heads to the House, which is expected to approve it. Gov. Chris Gregoire supports the measure and has said she will sign it into law.

-- The Associated Press contributed to this post