U.S. Sen. Robert Bennett (R-Utah) has backed off pushing an amendment aimed at overturning D.C.’s same-sex marriage law — most likely because his Republican colleagues joined Senate Democrats in opposing his plan to attach it to an aviation bill, according to Capitol Hill insiders.

The amendment, which Bennett filed with the Senate clerk March 11, would have prohibited D.C. from issuing marriage licenses to same-sex couples until the city allows voters to decide the issue through a referendum or initiative.

Bennett’s unsuccessful attempt to advance the amendment came as nearly 700 couples have applied for a marriage license at the city’s Marriage Bureau since the same-sex marriage law took effect March 3. Most of those couples have been same-sex couples.

And according to a spokesperson for the D.C. Superior Court, which operates the Marriage Bureau, an unprecedented number of people applying for marriage licenses are requesting to be married in civil ceremonies offered free of charge at the courthouse.

“We have probably close to 400 weddings requested,” said spokesperson Leah Gurowitz. “Between two-thirds and three-quarters [of couples applying for marriage licenses] are requesting a wedding at the Marriage Bureau.

“So we’re getting them scheduled. We’re calling everybody and we’re trying to just use our space and our time as advantageously as possible.”

Gurowitz acknowledged that late last week, the Marriage Bureau’s phone answering system became overloaded, and some callers received messages that the voicemail boxes were full and incoming messages could not be left.

“It’s taking some time — a day or two — to return calls,” she said. “But we are returning all the calls and getting the weddings set as soon as possible.”

Although Bennett filed his D.C. marriage amendment last week, he did not formally introduce it before Senate Democrats and Republicans agreed by unanimous consent to an approved list of amendments for a Federal Aviation Administration authorization bill, the measure to which Benefit intended to attach his amendment.

The bipartisan-approved list doesn’t include his amendment, preventing him from bringing it up at this time.

Bennett’s office did not return calls seeking to determine why he did not offer the amendment before the list restricting new amendments was approved.

“I doubt that he just voluntarily withdrew his amendment,” said Daniel Penchina, a lobbyist with the Raben Group, a political consulting firm that works with LGBT rights groups.

“My guess is they were trying to put together a package of amendments that could be considered and they agreed that his would not be part of it,” Penchina said. “And someone in his party leadership called and said, ‘Why don’t you save this for another day?’ That’s me speculating, but that’s probably what happened.”

Max Gleishman, press secretary for Sen. Richard Durbin (D-Ill.), the Senate’s majority whip, said Senate Republicans clearly supported a consent agreement that did not include the Bennett amendment.

“So I’m not sure why it wasn’t offered,” Gleischman said. “But it was not. And so therefore we’ve locked in, through a consent agreement, a finite list of amendments. And that’s not one of the ones on the list.”

Bennett’s proposed amendment, which was published in the March 11 Congressional Record, is identical to a freestanding bill that he and seven other Republicans introduced Feb. 2. The bill’s stated purpose is “to protect the democratic process and the right of the people of the District of Columbia to define marriage.”

According to the Congressional Record, Sens. Sam Brownback (R-Kan.) and Roger Wicker (R-Miss.) joined Bennett in filing the amendment as a proposed attachment to the FAA authorization bill, which is being considered on the Senate floor. The authorization measure is being pushed by Senate Democratic leaders and is considered essential for continued operation of U.S. aviation related programs, including the nation’s air traffic control system.

Both the amendment and Bennett’s free-standing bill say, “Notwithstanding any other provision of law, including the District of Columbia Human Rights Act, the government of the District of Columbia shall not issue a marriage license to any couple of the same sex until the people of the District of Columbia have the opportunity to hold a referendum or initiative on the question of whether the District of Columbia should issue same-sex marriage licenses.”

Paul Strauss, who lobbies the U.S. Senate as an informal shadow senator on D.C.-related issues, said unconfirmed reports that Bennett was planning to introduce an amendment to block the city’s same-sex marriage law surfaced last week on Capitol Hill.

“It could potentially force an up or down vote on gay marriage,” Strauss said. “This is certainly something that Democrats and at least some Republicans want to avoid.”

D.C. gay activist Bob Summersgill, who has coordinated local efforts to persuade the city government to support same-sex marriage equality, said Bennett and other lawmakers opposed to the marriage law are likely to launch a stronger effort to overturn it later this year.

“What we have to be most worried about is the D.C. appropriations bill,” he said, which usually comes up before Congress in late summer or fall.

Summersgill noted that while many lawmakers object to attaching a D.C. gay marriage amendment to an aviation measure or other unrelated bills, they would likely go along with attaching such an amendment to the city’s annual appropriations bill, which specifically addresses D.C. issues.

“It will be germane on that bill,” he said.

But as Bennett backed down on his marriage amendment, the National Organization for Marriage, which campaigns against same-sex marriage laws throughout the country, appeared to inject the gay marriage issue into the city’s upcoming mayoral election campaign.

Several local activists reported being contacted by an automated telephone poll on the D.C. gay marriage law that identified NOM as its sponsor. The activists said a recorded message stated that Mayor Adrian Fenty supports “gay marriage” and at least one of his lesser-known opponents in the 2010 mayoral race, former D.C. television news reporter Leo Alexander, opposes it.

D.C. resident Kevin Keller, who was among the people contacted for the phone poll, said it was obvious to him that the call was intended to stir up opposition to same-sex marriage rather than obtain an impartial assessment of how residents feel about the issue.

“I called Alexander’s campaign office, and we spoke,” Keller told DC Agenda. “He told me he opposes gay marriage on religious grounds, but he said he is not directly associated with the NOM.”

NOM executive director Brian Brown did not immediately return DC Agenda’s call on the matter. Local same-sex marriage opponents have vowed to work to defeat Fenty, who signed the same-sex marriage bill, and 11 of the 13-member City Council who voted for the bill when it passed in December.

But political observers say no serious candidates opposing gay marriage have surfaced so far to run against Fenty. And just a few people, whose chances are viewed as questionable, have emerged to run against Council members who voted for the marriage measure.

Alexander, who announced his candidacy in September, has raised less than $4,000 for his mayoral campaign, according to records filed with the D.C. Office of Campaign Finance. Records from the office also show that Fenty has raised more than $3 million for his re-election campaign.

D.C. Council Chair Vincent Gray (D-At Large), who has said he is considering running for mayor and is considered a viable candidate, voted for the marriage bill and, like Fenty, has been an outspoken supporter of same-sex marriage equality.

Another possible candidate for mayor, millionaire developer R. Donahue Peebles, has vowed to spend $5 million of his own money should he enter the mayoral race, making him a potentially serious contender. A Peebles spokesperson did not immediately return a DC Agenda call seeking to learn Peebles’ position on same-sex marriage.

Some reports have surfaced that he supports same-sex marriage but also favors a referendum or initiative to allow voters to decide the issue, but the reports could not be confirmed.

As developments surrounding the D.C. marriage law continue to unfold, many activists have said the joy experienced by the dozens of same-sex couples who have married or obtained marriage licenses so far has overshadowed the controversial aspects of the law.

Rev. Dwayne Johnson, pastor of the Metropolitan Community Church of Washington, which has a mostly gay congregation, said the church’s first same-sex wedding held March 14 had a profound impact on the more than 250 people in attendance.

Will Knicely and Bob Whitman, who have been together for more than 10 years and are MCC members, exchanged wedding vows as the church’s highly acclaimed chorus sang “Oh Happy Day,” said Johnson, who co-performed the wedding.

“I don’t think any of us were prepared for the emotion we witnessed,” he said. “It was like 39 years of hope culminating at that moment. People were applauding and applauding. We just let it go.”