By Paul Kane, The Washington Post

The Senate moved closer to passing a historic piece of legislation Monday that would ban discrimination against gay workers, signaling a dramatic shift in political attitudes on the issue.

Seven Republicans joined 54 members of the Democratic caucus in voting to formally begin considering the Employment Non-Discrimination Act (ENDA). The 61 to 30 margin virtually guarantees its passage this week.

It has been more than 17 years since the Senate voted on the issue, and Monday-s vote was a vivid illustration of how new political currents have forced lawmakers from both parties to catch up with an electorate that is increasingly supportive of gay rights. Fourteen states have legalized same-sex marriage, and a majority of Americans believe gay couples should have the right to wed.

Advocates still face long odds in getting the legislation to President Obama-s desk. House Speaker John A. Boehner (Ohio), who leads a GOP caucus dominated by social conservatives, reiterated his opposition to the measure Monday and said he would not bring it to the House floor regardless of its fate in the Senate.

But even in the face of obstacles, advocates say the debate has changed radically in their favor. They note that most opponents, including Boehner, have focused their concerns on allegations that the legislation would benefit trial lawyers and have shied away from the morality and family-values questions that once dominated the issue.

“There-s been a softer tone, and there-s been a recognition that anti-gay politics that may have worked in 2000 and in 2004 don-t work anymore,” said Jeff Cook-McCormac, senior adviser to the American Unity Fund, a pro-gay-rights group funded by Republican mega-donors.

The roll call on the vote produced a rare moment of Senate drama, as a trio of prominent Republicans – Sens. Kelly Ayotte (N.H.), Rob Portman (Ohio) and Patrick J. Toomey (Pa.) – holed up in the GOP cloakroom off the floor deciding at the last minute whether to back the legislation. Democrats needed those GOP votes to clear the 60-vote hurdle because a couple of supporters were absent.

Sen. Jeff Merkley (D-Ore.), the legislation-s main sponsor, negotiated with the GOP holdouts over the bill-s final details, and almost 40 minutes after the roll call began, the three Republicans voted for the measure.

A decade ago, the political calculation was far different. The brain trust of President George W. Bush-s reelection team encouraged a series of state ballot initiatives banning same-sex marriage as a way to draw more conservatives to the polls. In 2006, running into the head winds of a midterm election, Senate Republicans pushed legislation that would have imposed a federal ban on same-sex marriage – in large part because GOP advisers considered it a winning political maneuver, even as it fell well short of the two-thirds majority required to amend the Constitution.

Even when Democrats held 60 Senate seats in 2009, the majority did not advance ENDA, partly out of fear that some incumbents in conservative-leaning states would not be able to support the measure because of a potential political backlash.

Those attitudes have changed in the past four years, beginning with the vote in December 2010 to end the military-s ban on service by openly gay members.

Supporters of ENDA noted that 21 states and the District of Columbia have laws that prohibit workplace discrimination based on sexual orientation, and almost 10 more have some protections through executive orders by governors.

On Monday, after seven years in the minority, Senate Republicans provided the key margin to advance the gay rights bill, along with a handful of Democrats from deep-red states who a few years ago might have feared the political fallout from supporting the legislation.

In the hours leading up to the vote, no Republicans went to the floor to publicly oppose the measure. The only Republicans to speak were those in favor of the legislation, including Sen. Mark Kirk (Ill.), who used his first Senate floor speech since having a stroke almost two years ago to support the bill.

The other Republicans who supported the key procedural vote were Sens. Susan Collins (Maine), Dean Heller (Nev.) and Orrin G. Hatch (Utah).

The political push has been similar to the effort to end the “don-t ask, don-t tell” policy in the military, focusing on appealing to conservative values of wanting to help capable people join the workforce.

“We-re the party that focuses on the people-s ability to do the job,” said former senator Norm Coleman (R-Minn.), whom the American Unity Fund hired to lobby on behalf of the anti-discrimination measure.

A small but vocal bloc of conservative groups, including the Family Research Council and Heritage Action for America, has been trying to rally opposition to the legislation. “It would not protect equality under the law, but create special privileges that are enforceable against private actors,” Ryan Anderson of Heritage wrote last week.

Those groups, however, do not have the financial resources that the other side has, particularly American Unity, which has been seeded with donations from Paul Singer, the billionaire chief executive of a hedge fund. Another backer of the group is former Republican National Committee chairman Ken Mehlman, who was Bush-s 2004 campaign manager. Now a Wall Street executive, Mehlman announced in 2010 that he is gay.

The coordination between these Republicans and liberal gay rights groups would have been unthinkable a decade ago. Now, they are working hand in hand.

On Friday morning, Democratic press secretaries received a briefing on the non-discrimination legislation that was led by the Human Rights Campaign, a well-funded group supporting gay rights. The Democratic group received a briefing on polling that was delivered by Target Point Consulting, a GOP firm that once advised Mitt Romney.

Other GOP strategists have joined the effort, in part because of their own experiences with gay friends or relatives, and in part because many Republicans believe that their political survival in the long run depends on softening the party-s long-standing opposition to gay rights.

Target Point-s polling data showed that more than 80 percent of voters think that discrimination against gay workers is already illegal. When asked whether they support a federal law that “protects gay and transgender people from employment discrimination,” 56 percent of Republicans said yes, according to the firm-s polling.

That has been the message that Coleman and former congressman Thomas M. Reynolds (R-N.Y.), who is also lobbying for American Unity, have been pushing to GOP lawmakers. They have cautioned that this vote does not mean a lawmaker supports same-sex marriage but is instead voting to help the economy.

“It should be an easy vote for Republicans,” said Coleman, who remains opposed to same-sex marriage.

Even on that issue, attitudes are shifting quickly. In deep-red South Carolina, 52 percent of voters oppose same-sex marriage, but that number is down from 78 percent in 2006, when the state-s voters easily approved a constitutional amendment defining marriage as a union between a man and a woman.

In the House, 193 lawmakers have signed on as co-sponsors of the non-discrimination act, including a handful of Republicans.