Washington - The Senate passed a historic piece of gay rights legislation Thursday that would ban workplace discrimination against gay and transgender employees, another milestone victory for the gay rights movement that has been gaining favor in the courts and electoral politics.

The 64 to 32 vote to approve the Employment Non-Discrimination Act marked the first time federal lawmakers had approved legislation to advance gay rights since repealing the military's ban on gay men and lesbians in uniform in late 2010. Approval of the measure came two days after Illinois became the 15th state to legalize same-sex marriage and four months after the U.S. Supreme Court sanctioned federal recognition of legally married gay couples.

"This is a really tremendous milestone, a day I will never forget," said Sen. Tammy Baldwin, D-Wis., the first openly lesbian senator.

President Barack Obama praised supportive senators and called on House Republicans to quickly permit a vote.

"One party in one house of Congress should not stand in the way of millions of Americans who want to go to work each day and simply be judged by the job they do," Obama said in a statement. "Now is the time to end this kind of discrimination in the workplace, not enable it."

But ENDA faces a steep climb in a GOP-controlled House still dominated by social conservatives. House Speaker John Boehner, R-Ohio, and his lieutenants believe the measure is too broad and is unnecessary; they believe that the people ENDA is intended to protect are already covered under existing federal, state and private workplace protection laws.

Twenty-one states have laws prohibiting workplace discrimination based on sexual orientation, while 17 states also bar discrimination based on gender identity. Hundreds of the nation's largest companies also have similar bans.

The campaign to enact federal workplace protections for gays and lesbians began 17 years ago, and supporters have struggled ever since to earn a vote. But in the latest sign of shifting public opinion, every member of the Senate Democratic caucus present Thursday was joined by 10 Republican senators to approve the measure. In 1996 - the first time the Senate voted on a bill similar to ENDA - Sens. Orrin Hatch, R-Utah, and John McCain, R-Ariz., voted no. On Thursday, they voted yes.

"This is the right thing to do," McCain told reporters before he cast his vote.

Opponents stayed largely silent until Thursday, when Sen. Daniel Coats, R-Ind., said on the Senate floor that ENDA "diminishes" the religious freedom of organizations and employers who may feel compelled to hire people who hold religious views contrary to the organization.

"I oppose discrimination of any kind, and that includes discrimination, however, also, of individuals or institutions for their faith and values, which often gets lost and has been lost in this discussion," Coats said.

The conservative Family Research Council also warned that ENDA "would transform the workplace into an environment in which certain self-identifications and conduct must be given special privileges by employers" that might require people to suppress religious or moral views.

Those concerns are shared by Boehner, who reiterated his years-long opposition to the proposal in a statement this week. But supporters said Thursday that the House version of ENDA has at least 193 GOP cosponsors and that they are pursuing dozens more. Congressional Democrats also suggested that socially conservative Republicans are increasingly out of step with most Americans.

"Our history books are littered with those public figures who said, we just can't end that discrimination based on race; we can't end that discrimination based on age, based on disability, based on gender. Think about their place in history today," Sen. Dick Durbin, D-Ill., said.