Hawaii's legislators considered, on the one hand, a constitutional amendment that would limit marriage to heterosexuals and, on the other, a broad domestic partnership act.
"The state's statutory provisions limit marriage to a man and a woman," Mr. Blumenthal said.
The proposition, which would amend the state constitution to limit marriage between a man and woman passed and donor information became public.
Thirty-one states have constitutional restrictions limiting marriage to one man and one woman.
He has also voted against a constitutional amendment proposed in 2006 to limit marriage to being between one man and one woman.
Hawaii's voters then amended their Constitution to limit marriage to a man and a woman, but court cases continued to follow Hawaii's lead.