At least 5,500 additional voters will be able to cast their ballots in a closely-watched congressional special election runoff in Georgia next month after a federal judge ordered the state to extend its voter registration deadline, according to the Georgia Secretary of State’s office.

The race between Democrat Jon Ossoff and Republican Karen Handel has drawn national attention because of a swell of unexpected support for Ossoff. Republicans have long held the seat in Congress that the two are vying for.

Ossoff and Handel were the top two finishers in an April 18 special election. Neither candidate got 50 percent of the vote, so both advanced to a June 20 runoff. Federal law sets 30 days before an election as the earliest a state can cut off voter registration. Georgia had complied with that requirement ahead of the April special election, but said that anyone who had not registered by March 20 also could not vote in June.

Five civil rights and engagement groups sued the state over that requirement, and a federal judge ordered Georgia to extend the registration deadline until May 21.

Since March 20, the initial voter registration deadline, at least 5,500 new voters and voters transferred from other counties have been added the rolls in Georgia’s 6th District and will have a chance to cast a ballot in the June runoff, said Candice Broce, a spokesman for the Georgia Secretary of State’s office. The Atlanta Journal-Constitution, which first reported the 5,500 voter increase, reported that local officials are still processing thousands of applications from voters, who could be added to the rolls in time to vote in the runoff.

Handel, who served as Georgia’s Secretary of State from 2007 until 2010, has criticized the ruling to extend the voter registration deadline, suggesting Democrats are attempting to steal the election. There’s no indication that simply allowing more people to register to vote will actually benefit Democrats.

Earlier in May, The Telegraph in Macon, Georgia, reported that there were 464,000 more voter applications this year than in the last nonpresidential year.

Polling on the runoff has been scarce, but shows Ossoff at an advantage. Most surveys have found that the runoff will be an extremely close race, although the most recent, conducted by SurveyUSA, gives the Democrat a somewhat more substantial 7-point edge.

“Democracy is always better served when all eligible voters, regardless of party affiliation, can avail themselves of the right to exercise the most sacred right in our democracy. We are pleased that thousands more Georgia voters will be able to participate in future runoff elections for federal office,” said Kristen Clarke, head of the Lawyers’ Committee For Civil Rights Under Law, which brought the lawsuit on behalf of the five civil rights and engagement groups.

There are 524,430 registered voters in the 6th Congressional District, Broce said.

This article has been updated with a statement from Kristen Clarke.