President Bush threw what was left of his influence on Capitol Hill behind the move by social conservatives to amend the Constitution to discriminate against gays and lesbians. But when the votes were counted Wednesday, the president was not even able to muster a majority in the Senate.

When the critical test came on the election-year proposal to amend the Constitution to essentially ban same-sex marriage — along with a number of other basic protections for gay and lesbian families — only 49 senators voted to move the amendment forward.

That was far short of the 60 votes needed to invoke cloture, close off debate and force a vote on the actual amendment. And it was a full 18 votes short of the 67 needed for the Senate to approve a Constitutional amendment.

On a more politically pragmatic level, Wedesday’s tally put the ban one short of a majority in a Senate that is supposedly on the side of the president who has gone out of his way to make same-sex marriage an issue. So significant was the failure that White House press secretary Tony Snow felt compelled to report that Bush was not “despondent” over the result.

Perhaps he should be, as Bush’s inability to keep even his own partisans in line on an issue he has chosen to make something of a focal point of his second-term agenda was striking.

Seven Republicans — Lincoln Chafee of Rhode Island, Susan Collins of Maine, Judd Gregg of New Hampshire, John McCain of Arizona, Olympia Snowe of Maine, Arlen Specter of Pennsylvania and John Sununu of New Hampshire — voted with 41 Democrats to block cloture. [Two of the Republicans who opposed cloture, Gregg and Specter, had previously been amendment supporters but switched to the opposition Wednesday.] Only two Democrats who happen to be up for reelection this year in socially-conservative states, Robert Byrd of West Virginia and Ben Nelson of Nebraska, voted with 47 Republicans to end debate.

Notably, the three senators who did not vote Wednesday — Democrats Christopher Dodd of Connecticut and Jay Rockefeller of West Virginia, and Republican Chuck Hagel of Nebraska — have all expressed opposition to amending the Constitution to ban same-sex marriage. Hagel has been particularly blunt, telling a Nebraska newspaper in 2005, “I’m a conservative. I believe the sanctity of the Constitution of the United States is very important, I don’t think you need a constitutional amendment defining marriage. That’s a state issue.”

The amendment, which Senator Ted Kennedy, D-Massachusetts, correctly identified as “an instrument of bigotry and prejudice” will continue to rattle around the Capitol — look for a meaningless House vote on the issue next month — as Republicans try to use it as a tool to energize the party’s increasingly listless base. Senator Dick Durbin, D-Illinois, explained during the cloture debate, “This is not about the preservation of marriage. This is about the preservation of a [Republican] majority. I think, sadly, most people realize there’s political motivation here.”

Wednesday’s vote cannot provide much inspiration for the GOP, however. With so many of its own senators voting to block the amendment’s progress — including incumbents such as Chafee and Snowe who are up for election this year — the Republicans are going to have a hard time suggesting that expanding their party’s majority in the Senate will move the country any closer to a federal ban on same-sex marriages, civil unions and other protections for gay and lesbian families.

Indeed, there has been a good deal of grumbling within the Republican Senate caucus — as evidenced by the seven dissenting votes that were cast Wednesday — about the wisdom of trying to gin up a debate on social issues when the attention of the American public seems to be so firmly fixed on the war in Iraq and concerns about the strength of the economy and health care costs.

That won’t stop social conservatives from pushing their discrimination amendments. They’ll win in some states, as they did Tuesday in Alabama, where voters overwhelmingly approved a constitutional amendment Tuesday to ban same-sex marriage. But a similar amendment is on the ballot in Wisconsin this fall, and polls and pattersn suggest that it could be the first such state-based proposal to lose. More significantly, the high-profile, high-spending amendment fight in Wisconsin is expected to stir interest in the fall election on the part of young people and other traditionally low-turnout populations that Democratic strategists think will be drawn to the polls to oppose the amendment but stay around to vote for Democrats.

There’s no question that playing the discrimination card has helped Republicans by drawing socially-conservative voters to the polls in recent years. But the low-road approach seems to be wearing thin, even for Republicans. McCain, who some had predicted would vote for cloture and the marriage ban in order to improve his prospects among the social-conservative voters who will be key players in the 2008 Republican presidential nomination process, cast a firm “no” vote and then took a swing at the core argument for the amendment, telling the Senate, “Most Americans are not yet convinced that their elected representatives or the judiciary are likely to expand decisively the definition of marriage to include same-sex couples.”

That is true. It is also true that support for discrimination against gays and lesbians is waning in America, especially among younger voters. Time and experience are moving citizens toward what the first Republican president, Abraham Lincoln, referred to as “the better angels of our nature” — and away from the notion that sowing devisions and encouraging discrimination will somehow make either families or the Republic stronger.