ALBANY — The State Senate defeated a bill on Wednesday that would legalize same-sex marriage, after an emotional debate that touched on civil rights, family and history. The vote means that the bill, pushed by Gov. David A. Paterson, is effectively dead for the year and dashes the optimism of gay rights advocates, who have suffered setbacks recently in several key states.

The bill was defeated by a decisive margin of 38 to 24. The Democrats, who have a bare, one-seat majority, did not have enough votes to pass the bill without some Republican support, but not a single Republican senator voted for the measure. Still, several key Democrats who were considered swing votes also opposed the bill.

Mr. Paterson made an unusual trip to the Senate floor minutes after the last vote was cast, saying, “These victories come and so do the losses, but you keep on trying.”

It was not an issue that broke down among racial lines, or even religious and agnostic divisions. In fact, nine of the Senate’s 11 black members voted in support of same-sex marriage.

“When I walk thru these doors, my bible stays out,” said Senator Eric Adams, a Brooklyn Democrat who compared the law preventing same-sex marriage to laws that kept blacks and whites from marrying. “I believe there are certain moments here where we can benchmark our lives by the votes we took.”

The debate was as personal as any to take place in the Senate chamber in years. Senators spoke of their experiences as Jews and Baptists, as blacks and women. They spoke of spending long nights contemplating their votes and the deceased gay friends and relatives who inspired their decision.

Senator Ruth Hassell-Thompson, a Democrat who represents parts of the Bronx and Westchester County, spoke publicly for the first time about her gay brother, who was shunned by her family and moved to France.

“He had disappeared from our lives. And my father worried, but he could not ask him to come home,” she said, fighting back tears. Ms. Hassell-Thompson said she searched for her brother and eventually found him and asked him to come home. But he told her he was hesitant because he felt his family did not want to see him. “I said, ‘But your sister does.’”

But State Senator Rubén Díaz Sr. of the Bronx made an impassioned argument against same-sex marriage, describing his continued opposition as reflecting the broad consensus that marriage should be limited to a union between a man and woman. “Not only the evangelicals, not only the Jews, not only the Muslims, not only the Catholics, but also the people oppose it,” he said.

Senate Republicans had said before the vote that they believed their members could provide a few votes for the bill.

“There may be a few, that’s very possible,” said Senator Thomas W. Libous of Binghamton, the deputy Republican leader who said he will vote against the bill. “Everybody’s feeling is get it on the floor and let’s vote it up or down. It’s been talked about enough. Let’s get it done. I think it’s going to be very close.”

Ms. Krueger said before the debate began that she was optimistic the bill would pass, but added, “It depends on whether Republican votes are delivered.”

Had the legislation passed, New York would have become the sixth state where marriage between same-sex couples is legal or will soon be permitted. But now that it has failed, New York becomes the latest state where gay rights advocates have made considerable progress only to see their hopes dashed.

Last month Maine became the 31st state to block same-sex marriage through a referendum. The Maine State Legislature had voted to legalize same-sex unions earlier this year, but opponents of gay rights gathered enough signatures to put the measure on the ballot.

Last year, California voters repealed same-sex marriage after the State Supreme Court said that gay couples had the right to marry.

Unlike in Maine, however, New York does not have a referendum process that allows voters to overturn an act of the Legislature.

The State Assembly had already approved the legislation, and Gov. David A. Paterson had said he would immediately sign the bill if it made it to his desk.

Shortly after midnight on Wednesday, the Assembly voted 88 to 51 to allow same-sex marriage. Though the Assembly has already passed the bill twice, a quirk in New York’s legislative code required the Assembly to pass the bill again before the governor can sign it.

As the vote approached advocates on both sides of the debate were pushing ahead with a last-minute effort to shore up support.

“We’re working it as hard as we can,” said Senator Eric T. Schneiderman, a Democrat who represents the Upper West Side and who supports same-sex marriage. “It feels very good right now. It feels like its going to happen. But this is an issue where some people don’t want to declare themselves until the last minute. And I think, believe it or not, I think there are one or two people who are really still torn.”

Demonstrators on both sides of the issue were relatively scarce in the Capitol on Wednesday. A small group of Orthodox Jews gathered outside the Senate chamber, one of them holding a sign that read “Gay Union/A Rebellion Against the Almighty.”

Rabbi Yisroel Dovid Weiss of Monsey, N.Y., said he traveled to Albany to remind the Senate “that the world belongs to the Almighty, and they have to reckon with his rules and his law.”

As John L. Sampson, the Senate Democratic leader, walked into his office on Wednesday morning, he flashed a thumbs-up to same-sex marriage supporters standing a few feet from the protesters. But Mr. Sampson acknowledged he did not know how the vote would turn out.

“I’ve got my work cut out for me,” he said.