By Sean Sullivan , Beth Reinhard and Amy Gardner

Florida’s historic recount was thrown once more into uncertainty Thursday when a federal judge ruled that at least 4,000 voters whose mail-in and provisional ballots were rejected because of issues with their signatures may be given two days to resolve the problem and have their votes counted.

The decision by Judge Mark Walker of the U.S. District Court in Tallahassee came hours ahead of the Thursday afternoon deadline for elections officials to complete a machine recount. Early Thursday, officials in Broward County finished their count and prepared to release a new vote total for Florida’s second-largest jurisdiction.

It was not clear how the judge’s decision would affect the timing of recount, which was expected to move to a manual canvass Friday in the too-close-to-call Senate race, in which Gov. Rick Scott (R) leads Sen. Bill Nelson (D) by fewer than 13,000 votes.