A bill passed this week in Washington grants same-sex domestic partners the same rights and benefits the state offers to straight married couples.
AP reports that the House approved the Senate-passed measure 62-35 vote after nearly two hours of debate.
Governor Chris Gregoire has confirmed she will sign it into law when it reaches her desk.
“Our state is one that thrives on diversity,” she said in a statement. “We have to respect and protect all of the families that make up our communities.”
The bill will allow references to partnerships to be added alongside all remaining areas of state law where currently only married couples are mentioned.
This will affect labour and employment rights, along with pensions and other public employee benefits.
Domestic partnerships were brought into law in the state in July 2007 and more than 5,000 have been filed so far.
Democrat representative for Seattle Jamie Pedersen, a gay lawmaker who sponsored the bill, said: “This bill completes our work on domestic partnerships by making sure that we state clearly our intention to treat domestic partners in our state equally.”
However, religious groups have confirmed their intentions to place a measure to repeal the new bill on the November ballot.
They have argued that granting same-sex partners every right of marriage except in name will lead to a detrimental effect on traditional marriage.
“We cannot elevate the legal standing of domestic partnerships to equate with marriage and not have profound impact on the status of marriage in this state,” said Jay Rodne, a Snoqualmie Republican.