Today is a make-or-break day for the District of Columbia House Voting Rights Act, as the Senate is scheduled to vote on a procedural motion that would advance the measure for limited debate and a vote.

But whether Democrats have the 60 votes needed to invoke cloture on the bill remained unclear Monday. Five Republicans and almost all of the 51 members of the Democratic Conference have gone on the record in favor of the measure, leaving just a handful of votes up in the air.

If the cloture motion fails, it would be a massive setback for the voting rights effort, potentially dooming the bill this Congress. Still, backers of the bill remained optimistic Monday, saying they are confident the motion will pass.

“We’ve got the right team, we’ve got the right city, we’ve got the right issue,” D.C. Mayor Adrian Fenty (D) told supporters outside the Dirksen Senate Office Building. “And I actually think we’ve got the right Congress as well.”

Sen. Joe Lieberman (ID-Conn.) joined Utah Sens. Orrin Hatch (R) and Bob Bennett (R) in sponsoring the compromise bill, which would grant the District a full vote in the House while also giving one to Utah.

The measure passed in the Lieberman-chaired Homeland Security and Governmental Affairs Committee by a 9-1 vote in June, with ranking member Susan Collins (R-Maine) and fellow GOP Sens. George Voinovich (Ohio) and Norm Coleman (Minn.) crossing the aisle in support.

Lieberman spokeswoman Leslie Phillips reaffirmed Monday that the Senator is confident supporters have the votes to pass the cloture motion.

But opposition will certainly be fierce.

Senate Minority Leader Mitch McConnell (R-Ky.) has been outspoken against the bill, which he repeatedly has labeled unconstitutional.

McConnell took to the floor on Monday afternoon to explain his beliefs, pointing to Article 1, Section 2 of the Constitution, which states Members of the House shall be chosen by “the People of the several States.”

There’s no question that the framers of the Constitution intended the federal city to be a separate entity from the states, which Congress could control, he said.

“To vote for it would violate our oath of office, in which we solemnly swear to support and defend the Constitution,” McConnell said. “If the residents of the District are to get a Member for themselves, they have a remedy: Amend the Constitution.”

McConnell definitely will vote against the cloture motion, spokesman Don Stewart confirmed Monday evening. But Stewart said he did not know whether Republicans had the votes needed to block cloture.

“I gave up predicting the last time I was in Vegas,” Stewart joked.

Advocates had hoped McConnell would stand down and let the bill move forward. A group of civil rights leaders, including several from McConnell’s home state, met briefly with the Minority Leader on Monday afternoon to persuade him to let the bill move to a debate.

The group was downtrodden as they exited McConnell’s leadership office, calling the meeting courteous but disappointing.

“The 60-vote threshold has been set,” said Nancy Zirkin, vice president of the Leadership Conference on Civil Rights.

McConnell told the group he is not opposed to District voting rights per se, but against this particular measure, and would use “every procedural device” to block its passage, they said.

“He indicated that he is opposed to it, and he was very forceful,” said Raoul Cunningham, president of the Louisville, Ky., branch of the NAACP.

Even if the Senate eventually approves the bill (if cloture passes, Senate Majority Leader Harry Reid [D-Nev.] could put it aside to focus on other bills), it is not ensured of enactment. White House officials have said they will recommend to President Bush that he veto the measure, but the president has not made any public remarks on the issue himself.

The mood outside McConnell’s office was a far cry from the mood outside Dirksen earlier in the day, when dozens of voting rights supporters, including Fenty, D.C. Del. Eleanor Holmes Norton (D) and several members of the D.C. City Council, turned out for a mid-morning press conference and rally.

Ex-Rep. Jack Kemp (R-N.Y.), who has lobbied heavily for the measure, told the crowd that the GOP had a long history of supporting civil rights issues and then backing away from it.

“Republicans, vote your conscience, vote the right way, and get on the right side of history,” Kemp said.

Norton unveiled a letter she sent to Senators Monday asking for their support. It was not written from a Member of Congress, she said, but rather as a longtime D.C. resident.

The Congressional Black Caucus and Congressional Hispanic Caucus also sent letters to Senators asking for support for the bill.

Among those attending Monday’s rally was D.C. Shadow Rep. Mike Panetta (D), who said he wants nothing more than to “not have to run for re-election for this job.”

Panetta noted that today marks the closest that D.C. voting rights advocates have come to getting full voting rights in a generation.

But he also noted that failing to get the 60 votes would be a major setback for the effort.

“If we don’t get the votes,” he said, “I don’t know what we are going to do.”