D.C. voting rights advocates experienced a bit of unexpected anxiety Friday when they learned that freshman Sen. Kay Hagan (D-N.C.) might not vote in favor of the D.C. House Voting Rights Act.

Voting rights group DC Vote sent its North Carolina supporters an e-mail Friday afternoon, asking them to call their Senator on behalf of the bill. Advocates have assumed that Democrats would vote for the bill, helping ensure that it would receive the 60 votes needed to prevent a filibuster in the Senate.

By early evening, Hagan spokesman David Hoffman said the newly elected Senator would at least support the cloture vote, scheduled for Tuesday.

“Sen. Hagan is going to vote in favor on cloture because she believes the bill deserves a debate,” Hoffman said. But, he added, she hasn’t yet decided whether she will vote for the bill and is “currently reviewing the underlying bill.”

Ilir Zherka, executive director of DC Vote, said the organization is not taking any chances. In 2007, the bill passed the House and came just three votes short of 60 in the Senate.

This time, Zherka said he thinks the bill has more than the 60 needed, but he is not making any predictions until the Senate votes Tuesday.

“You know the Senate is a tricky place,” he said. “Our opponents are very smart and very determined to stop it. Last time, in 2007, we thought we had enough votes. We thought we had 61.”

Opponents to the bill — mostly Republicans — say it is unconstitutional because Washington, D.C., is not a state and thus can’t have a voting Representative. Currently, D.C. Del. Eleanor Holmes Norton (D) can only vote in committee, not on the floor.