Delaware on Tuesday became the 11th state to permit same-sex marriage, the latest in a string of victories for those working to extend marital rights to gay and lesbian couples.
The marriage bill passed the State Senate by a vote of 12 to 9 Tuesday afternoon, and Gov. Jack Markell, a Democrat, was expected to sign it immediately, allowing same-sex couples to apply for marriage licenses on July 1.
Adoption of same-sex marriage by Delaware came just five days after a similar decision in Rhode Island and followed ballot-box victories last fall in Maine, Maryland and Washington.
During three hours of emotional debate preceding the vote Tuesday, State Senator Karen Peterson, a Democrat, said that she had lived with a female partner for 24 years, and she challenged those who opposed extending marriage to gay couples. "If my relationship hurts your marriage, then you need to work on your marriage," she said, eliciting cheers and laughter.
A Republican opponent of the bill, Senator Greg Lavelle, said before the Senate vote, "We won't fully understand the impact of this legislation for years to come." Mr. Lavelle, the minority whip, said it was "strange" to "have to defend traditional marriage that we have known for thousands of years."
In Maine, Maryland and Washington in November, same-sex marriage won in state referendums for the first time. In eight other states, now including Delaware, and in the District of Columbia it has been adopted by legislatures or required by court decisions.
Public opinion on the issue is shifting quickly, with polls showing that a majority of Americans now support allowing gay and lesbian couples to marry.
"The momentum continues," said Evan Wolfson, president of Freedom to Marry, a New York-based advocacy group that aided the campaign in Delaware.
Gay rights groups are hopeful that same-sex marriage will pass soon in Minnesota, where House members are expected to consider it later this week, and in Illinois, where the Senate has approved a bill but a vote has not been scheduled in the House.
But short of a sweeping decision by the Supreme Court that same-sex marriage is a right, change could come more slowly in the coming years. Thirty states have adopted constitutional amendments limiting marriage to a man and a woman -- measures that can only be reversed with public ballots.
"We're not discouraged," said Brian Brown, president of the National Organization for Marriage, which has helped finance opposition to same-sex marriage proposals across the country.
"The states that have passed same-sex marriage are deep blue liberal states," Mr. Brown said, arguing that his opponents usually find it easier to win in legislatures than in popular votes.
Both sides are waiting for the Supreme Court to announce two decisions this June that could alter the marriage landscape.
In one case the court will decide whether the federal government should recognize same-sex marriage in states where it is legal. In the other, it will decide the fate of California's Proposition 8, which banned same-sex marriage in the state after a court had declared it a legal right.
Rita K. Farrell contributed reporting from Dover, Del.
This article originally appeared in The New York Times.