Some 30,000 absentee ballots in Milwaukee need to be recounted, likely delaying the results in the key swing state of Wisconsin, election officials said.

Milwaukee's central count location will rerun about 31,000 ballots after a "sealing" error with the tabulation machines was discovered.

About 30,000 ballots in Milwaukee will have to be recounted due to a tabulator issue, the city said on Tuesday afternoon.