Advocates of the District of Columbia House Voting Rights Act will head to the Senate this week in an attempt to lock down the 60 votes needed to avoid a filibuster, and supporters already have begun by targeting Sens. Arlen Specter (R-Pa.) and Jim Webb (D-Va.).

While Specter and Webb are the first Senators being named in public, proponents are planning to lobby about a dozen offices as part of the overall effort on behalf of the measure, said Ilir Zherka, executive director of the advocacy group DC Vote.

And on Wednesday, a small group of the bill’s supporters will visit about 25 Senate offices to lobby, thank selected Senators for their ongoing support and just try to find out where the bill stands, Zherka said.

“It’s really about [getting] in, getting some intelligence,” Zherka said. “It’s a more targeted lobby effort than some of the more public things we’ve done in the past.”

Webb has said he supports D.C. voting rights but has not yet decided whether to support this particular piece of legislation.

Specter also has not taken a position on the bill, an aide said Monday. But “he seems like a natural ally,” according to Zherka, who cited Specter’s support of the Voting Rights Act renewal last year.

The Senator’s role as ranking member on the Judiciary Committee and the fact that he hails from Pennsylvania — where many of DC Vote’s coalition partners are based — also make him a potential backer, Zherka said.

Voting rights supporters would not reveal the other Senate offices that will be targeted in the lobby effort, although Zherka did confirm that the list is primarily made up of Republicans.

“On the Democratic side, it’s mostly a question of checking in and making sure folks are on board,” Zherka said.

Sponsored by Sens. Joe Lieberman (ID-Conn.), Bob Bennett (R-Utah) and Orrin Hatch (R-Utah), the measure would grant D.C. a full vote in the House while also giving one to the Beehive State, which just missed getting a vote following the 2000 Census.

The bill passed the Lieberman-chaired Homeland Security and Governmental Affairs Committee in a 9-1 vote last week, gaining the support of three more Republicans — ranking member Susan Collins (Maine) and Sens. Norm Coleman (Minn.) and George Voinovich (Ohio).

A Democratic committee aide said Monday that about 50 votes have been secured for the measure, and supporters are optimistic that they can reach the 60 needed to override a potential filibuster.

“This is really the year to do it,” the aide said of the bill. “I think we are all very excited. After that hearing — 9 to 1 was a big statement.”

Members also are working the halls in an attempt to get the 60 votes. D.C. Del. Eleanor Holmes Norton (D) “is meeting and speaking with Senators about the bill,” spokeswoman Doxie McCoy confirmed Monday.

(The House version of the bill, sponsored by Norton and Rep. Tom Davis [R-Va.], passed that chamber in April.)

And at the markup last week, Collins said she would work with members of her Conference to help achieve passage.

But major challenges still remain.

Senate Minority Leader Mitch McConnell (R-Ky.) has labeled the bill “blatantly unconstitutional” because it grants Congressional representation to a non-state.

White House aides repeatedly have said they would recommend that President Bush veto the bill should it reach his desk, citing similar constitutional concerns.

And even if Bush eventually decides to sign the measure, a court challenge is expected. Anticipating a lawsuit, the Homeland Security and Governmental Affairs Committee adopted a Collins-backed amendment that would expedite such a challenge.

Still, advocates remain optimistic. They cite the Constitution’s District Clause, which grants Congress the right to tax and extend court jurisdiction to D.C. residents, as the legal backing for the measure.

The key will be getting the votes to move the measure through the Senate.

“We don’t have 60 hard yeses,” Zherka said. “But we’re getting real close.”