An outlaw on same-sex marriage in Wisconsin came one step closer after the state Senate approved an amendment to the state constitution that would define marriage as the exclusive union of one man and one woman.

With a final tally of 20 to 13, the Senate passed the resolution early March 12. The vote was largely partisan, with 18 Republicans and 2 Democrats supporting the amendment and 13 Democrats opposing it.

The Senate’s passage of the controversial proposal came a week after the Assembly endured an all-night Democratic filibuster before passing the amendment by a 68 to 27 vote.

The amendment, which prohibits gay marriage or any, “legal status identical or substantially similar to that of marriage,” must now be passed by the full legislature again next session. If it secures a simple majority in both the Senate and the Assembly in two consecutive sessions, it can then be put up for public referendum as early as April 2005.