Proponents of the District of Columbia House Voting Rights Act vowed to keep fighting Tuesday after the Senate voted against cloture on the bill, a move that could doom its chances of passage during the 110th Congress.

Supporters blamed significant pressure from Republican leaders for the bill’s failure, saying they had the 60 votes needed to bring the measure to the floor in the morning only to lose a handful by the afternoon. The final tally wound up at 57-42 in favor of cloture.

D.C. Del. Eleanor Holmes Norton (D) identified GOP Sens. Thad Cochran (Miss.), John McCain (Ariz.) and Gordon Smith (Ore.) as bill supporters whom advocates had lined up but lost by the 2:30 p.m. vote.

“You’ve got to appreciate what happened in their caucus,” Norton said. “Extraordinary pressure.”

Cochran and McCain could not be reached by deadline.

In a statement, Smith said: “The District of Columbia should find its congressional franchise through the state of Maryland, by statute or through the Constitutional amendment process. I would support either effort.”

D.C. Shadow Rep. Mike Panetta (D), a leader in grass-roots efforts for the movement, found the silver lining, saying the vote list gives advocates a way to target Members.

“That’s something that is very valuable,” he said.

The compromise bill, sponsored by Sens. Joe Lieberman (ID-Conn.), Orrin Hatch (R-Utah) and Bob Bennett (R-Utah), would give Democratic-leaning D.C. a full House vote while also giving one to largely Republican Utah, which just missed getting an additional Representative following the 2000 Census.

The brainchild of Rep. Tom Davis (R-Va.), the bill had bipartisan support in both chambers (it passed the House in a 241-177 vote in April). Still, it was viewed largely as a partisan measure, as top Republicans labeled it unconstitutional, including Senate Minority Leader Mitch McConnell (Ky.) and advisers to President Bush.

McConnell had been especially vocal in his opposition in recent days, including a Monday appearance on the Senate floor in which he urged D.C. residents to push for a constitutional amendment instead.

The bill is “clearly and unambiguously unconstitutional” because it gives Congressional representation to a non-state, McConnell said.

“We in this body have a duty to defend the Constitution as the supreme law of the land,” he added.

The White House Office of Management and Budget also reaffirmed its disapproval of the bill Tuesday, releasing a statement of opposition and promising to recommend a presidential veto if the measure were to pass.

Meanwhile, backers of the bill praised Republicans who did cross the aisle in favor of cloture, including Sens. Norm Coleman (Minn.), Susan Collins (Maine), Dick Lugar (Ind.), Olympia Snowe (Maine), Arlen Specter (Pa.) and George Voinovich (Ohio).

Democrats did lose one of their own when Sen. Max Baucus (Mont.) voted against cloture. In a statement, Baucus said he voted to block the measure because it would dilute Montana’s influence in the House.

“It’s also a slippery slope,” he said. “If we expand the playing field now, then who is to say where it will stop? Will we give votes to territories, protectorates and commonwealths?”

Baucus added that he supports a proposal to allow D.C. residents to be represented as part of Maryland.

Despite the setback, supporters expressed optimism following the vote, noting that getting the 57 votes in the Senate is the farthest the movement has come in decades.

“I’m not discouraged, because — I’m not happy, either — but I’m not discouraged because I’ve seen a lot of these,” Hatch said. “It isn’t over, and ultimately, we are going to win this.”

Lieberman said he was “deeply disappointed and deeply outraged” that the Senate could not move to allow debate and a vote on the bill.

“It was bipartisan, and nonpartisan in its effect,” Lieberman said.

Davis called the vote a “high-water mark” in the voting rights effort and he vowed to continue to push for the measure. Norton, who co-sponsored the bill with Davis in the House, made the same promise.

“The fat lady has not sung yet. This war is not over,” Norton said. “You’ve got to understand how a war works. This is a battle.”

House Majority Leader Steny Hoyer (D-Md.) also weighed in, saying he will continue to work to see that D.C. gets representation.

“Those who argue this is unconstitutional because the vote can only be extended to citizens of the states should remember that everyone living in Washington, D.C., is in fact a successor of my home state of Maryland, which ceded land to create the District of Columbia,” Hoyer said.

D.C. Mayor Adrian Fenty (D), who used his Senate floor privileges to do some last-minute lobbying for the measure, said the city’s population would not be satisfied until they receive representation.

“Today the residents of the District of Columbia did not get what we deserve,” he said. “But tomorrow we will.”

Members of the D.C. City Council attended the vote, alongside an array of civil rights leaders and D.C. citizens. Many said they were disappointed yet determined to keep going.

“I really didn’t want to have to run again,” said Panetta, whose position would be eliminated if the bill becomes law.

It wasn’t all bad news for D.C. residents Tuesday. In a 96-0 vote, the Senate did move to reauthorize the Davis-sponsored D.C. College Access Act, which allows the city’s high school graduates to attend colleges outside the District at in-state rates.