Officials with the U.S. Postal Service and the Madison City Clerk's office confirm to News 3 an investigation is underway into what has happened to a number of absentee ballots in the City of Madison.

Madison City Clerk Maribeth Witzel-Behl said more than 1,700 ballots were mailed to indefinitely confined voters in the city. Ballots were dropped at the Madison Municipal Building post office on Sept. 22 to be mailed to voters. Since then, the office has been getting calls from voters who hadn't yet received their ballots.

"We have heard from some indefinitely confined households where one member of the household received their ballot, and the other did not," Witzel-Behl said.

So far, the Clerk's office has re-issued about 50 absentee ballots to voters who have not yet received a ballot. Five hundred voters have already returned their absentee ballot to be counted. It's unclear how many of the ballots may be missing.

Vicki Anderson contacted News 3 to say she hadn't received her ballot and had called to ask what happened.

"It is concerning," Anderson said. "With everything going on with voting right now with the IDs and the way the campaigns are being run, everything about it, and to have the ballots not show up is concerning."

A spokesman for USPS said an investigation is underway.

"Procedures are in place to monitor the processing and delivery of Election/Political mail," USPS spokesman Sean Hargadon said in a statement. " These concerns are a high priority for the Postal Service and we will work swiftly to resolve any issues."

Hargadon also advised the public to contact their local post office if they have concerns regarding their mail.