The Justice Department will have at least 780 observers at key polling places in 23 states to ensure compliance with the 1965 Voting Rights Act and look into any allegations of voter fraud.
Provisional ballots were the latest legal skirmish in the critical battleground state of Ohio, where Secretary of State Jon Husted's decision on how they can be cast was challenged in federal court. Advocates and lawyers for labor unions contend Husted's order would lead to some provisional ballots being rejected improperly because the burden of recording the form of ID used on a provisional ballot is being placed on voters, not poll workers as in the past.
A provisional vote allows a person to have his or her say, but the ballot is subject to review and verification of eligibility.
A decision was not expected before Election Day, but the judge overseeing the case planned a ruling before Nov. 17, when provisional ballots can begin to be counted in Ohio. Provisional ballots are used more often in Ohio than in most states, with experts predicting between 200,000 and 300,000 will be cast there.
"That could be a huge problem after Election Day for counting ballots," said Wendy Weiser, director of the Brennan Center's Democracy Program. "There's really tens of thousands of voters in Ohio whose votes could be at risk."