Romney's campaign on Monday asked the Wisconsin Government Accountability Board to extend it after some ballots were mailed passed the Sept. 22 deadline.
Wisconsin elections chief Kevin Kennedy says in a response letter made public Thursday that 37 ballots were affected and all have been transmitted to voters in time for them to complete them and get them back in time to be counted.
Kennedy says the state has been working with the U.S. Justice Department on the issue.
Romney's campaign raised similar complaints in Vermont, Mississippi and Michigan.
A spokesman for Romney's campaign did not immediately return a message.