The National Organization for Marriage (NOM) has pledged $250,000 to work against Republicans who vote for a proposed gay marriage law in Washington state.

Senator Ed Murray last week filed a bill that would make Washington the seventh state to legalize gay marriage.

The state currently recognizes gay couples with domestic partnerships. A 2009 expansion of the law gave gay couples all the protections of marriage. A ballot initiative to repeal the law failed.

“It's fairly incredible that some legislators would try to legalize homosexual marriage so soon after giving same-sex couples all the rights and privileges of marriage through Domestic Partnerships,” said NOM President Brian Brown in a statement. “This effort proves that the question is not one of rights but preserving marriage as a child-focused institution that has served families since the dawn of time.”

“We intend to hold every legislator accountable for his or her vote on marriage. Any Republican who votes to redefine marriage can count on funding of a primary challenge to them.”

Currently, two GOP Senators – Steve Litzow of Mercer Island and Cheryl Pflug of Maple Valley – and two Representatives – Glenn Anderson of Fall City and Maureen Walsh of Walla Walla – have thrown their support behind the bill. Several additional Republicans have said they remain undecided.

All four of the Republican state senators who helped New York pass a gay marriage law have seen sharp increases in their fund raising in the six months since the bill passed.

(Related: NOM pledges $500,000 to derail gay marriage in New Jersey.)