WASHINGTON (AP) — The Senate is moving forward on the first major bill barring workplace discrimination against gays in nearly two decades as Americans' shifting views about homosexuality have significantly changed the political dynamic.

Seven Republicans and 54 Democrats stood together Monday and cleared the bill past its first hurdle on a 61-30 procedural vote, setting the stage for debate on Tuesday and possible passage by week's end. The Employment Non-Discrimination Act would prohibit workplace discrimination against gay, bisexual and transgender Americans.

The legislation, the first significant gay rights bill since Congress ended the ban on gays serving openly in the military in 2010, faces strong opposition in the House, with Speaker John Boehner, R-Ohio, rejecting the measure.

Final passage would cap a 17-year quest to secure Senate support for a similar discrimination measure that failed by one vote in 1996, the same year Congress passed and President Bill Clinton signed the Defense of Marriage Act, the law prohibiting federal recognition of same-sex marriage.

"I think back to Martin Luther King's commentary that the great arc of the universe bends toward justice and I feel that our notion of fairness about employment, how central that is to pursuit of happiness, how central it is to equality, how central it is to the golden rule .... means that we will accomplish this," said Sen. Jeff Merkley, D-Ore., a chief sponsor of the bill. "But I do hope it's sooner rather than later."

Americans have displayed a greater acceptance of homosexuality while Republicans, who struggled to win over young people and independents in the 2012 presidential election, have searched for supporters beyond their core base of older voters. The Supreme Court in June affirmed gay marriage and granted federal benefits to legally married same-sex couples while same-sex marriage is legal in 14 states and the District of Columbia.

A Pew Research survey in June found that more Americans said homosexuality should be accepted rather than discouraged by society by a margin of 60 percent to 31 percent. Opinions were more evenly divided 10 years ago.

About a half hour after the Senate acted, President Barack Obama cited the vote as an example of "common sense starting to prevail" in a Congress that has opposed much of his agenda.

"Inexorably, the idea of a more tolerant, more prosperous country that offers more opportunity to more people, that's an idea that the vast majority of Americans believe in," the president told a group of supporters gathered for a summit in Washington Monday night.

In high drama for the Senate, the typical 15-minute vote stretched beyond 30 minutes of waiting and cajoling.

Two backers of the measure — Sens. Claire McCaskill of Missouri and Lisa Murkowski of Alaska — were on planes back to Washington. That left sponsors stuck at 58 of the necessary 60 votes, forcing Sen. Susan Collins, R-Maine, and Merkley to lobby fiercely, sometimes at the door of the Republican cloakroom off the Senate floor.

Minutes into the vote, Sen. Kelly Ayotte of New Hampshire emerged to vote yes. Then the outcome rested with Sens. Rob Portman of Ohio, who announced earlier this year that his son was gay and he supported same-sex marriage, and Sen. Pat Toomey of Pennsylvania.

After extended discussions, Portman and Toomey emerged to vote yes.

"I have long believed that more legal protections are appropriate to prevent employment discrimination based on sexual orientation," Toomey said in a statement after the vote, in which he promised to offer an amendment to protect religious freedom.

The other Republicans who voted yes were Sens. Orrin Hatch of Utah, who had opposed the discrimination measure in 1996, Dean Heller of Nevada, and Mark Kirk of Illinois.

Kirk delivered his first speech on the Senate floor since suffering a stroke in January 2012. Seated at a desk, Kirk said it was especially important for an Illinois Republican to speak out for the legislation in the tradition of Everett Dirksen and Abraham Lincoln, two leaders on civil rights.

"Attitudes are changing very rapidly on gay rights issues and we're seeing that with each passing day. More and more people have embraced equality," Collins said.

In Maine, six-term Democratic Rep. Mike Michaud, who is running for governor, said he was gay and questioned whether it still mattered to voters, a stark reminder of changing views, lingering resistance to homosexuality and uncertainty about the political implications.

The three potential Republican presidential candidates — Marco Rubio of Florida, Ted Cruz of Texas and Rand Paul of Kentucky — voted against, a reflection that among core GOP conservative voters opposition to gay rights remains strong. No senator spoke in opposition to the measure during Monday's debate.

Tony Perkins of the conservative Family Research Council said in a statement that he was disappointed in the Senate vote, but "confident that the U.S. House of Representatives will ultimately reject ENDA because it not only threatens the free market but religious liberties as well."

Current federal law prohibits discrimination on the basis of sex, race and national origin. But it doesn't stop an employer from firing or refusing to hire workers because they are gay, lesbian, bisexual or transgender.

The bill would bar employers with 15 or more workers from using a person's sexual orientation or gender identity as the basis for making employment decisions, including hiring, firing, compensation or promotion. The bill would exempt religious institutions and the military.