State lawmakers are calling for an investigation into how three tubs of undelivered absentee ballots from Fox Valley voters were found after Tuesday's election.

Sen. Dan Feyen, R-Fond du Lac, who represents the 18th Senate District that includes Oshkosh, said Wednesday that after he filed a complaint with the Wisconsin Elections Commission, he learned a U.S. Postal Service worker called the commission to report finding "three large tubs of absentee ballots from voters" in Oshkosh and Appleton.

It remained unclear Wednesday afternoon who exactly found the ballots and where or why they were not found or counted in Tuesday's election, but Feyen said in a statement he was working with the commission and would post updates later on.

"I understand your frustration and am working hard to try and remedy the situation," Feyen said in the statement.

Feyen's office believes the ballots had not been delivered to voters before the election, but continues to work with the Elections Commission to get the matter sorted out, Feyen spokesman Matthias Censky said Wednesday afternoon.

The coronavirus pandemic set off a flurry of requests for absentee ballots so voters would not have to go to the polls and possible expose themselves to the virus.

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Meagan Wolfe, the administrator of the Wisconsin Elections Commission, said she is looking into the situation. She said she has not determined whether the ballots had been on their way to voters or already filled out and on their way back to clerks.

"We don’t have answers on that at this point," Wolfe said during an online media briefing Wednesday afternoon.

Feyen wants the commission to go to court to give the voters a chance to have the ballots counted, according to his office.

Dozens of Oshkosh voters have taken to social media in the past couple weeks to express frustrations about requesting ballots as many as three weeks ago but did not get them by Election Day. One voter told an Oshkosh Northwestern reporter that when he called Oshkosh City Hall last week to ask about the status of his ballot, he was told the delay was due to a staffing shortage at the U.S. Postal Service facility in Milwaukee.

Even the state's top Assembly Democrat said he didn't get his absentee ballot ahead of Tuesday's election.

"I did not receive my ballot and was unable to vote & abide by the public health order," Assembly Minority Leader Gordon Hintz said Wednesday morning in a Facebook post.

Citing an Elections Commission database, Hintz said his ballot was mailed to him March 24.

In a statement late Wednesday afternoon, the Oshkosh Democrat said the issues weren't surprising, "given the surge in demand and chaos of having an election that did not need to, and should not have been held during this public health emergency."

Hintz urged the Elections Commission and the state Department of Justice to investigate the situation, along with any other reported regularities. He also called on the Legislature to implement secure, mail-only voting for the May, August and November elections.

"This should be an immediate priority," he said.

As of Wednesday morning, clerks in Winnebago County had gotten back 12,319 of the 14,287 absentee ballots they previously sent out, according to the Elections Commission. In Outagamie County, 30,361 of 40,344 ballots had been returned.

Meanwhile, the Milwaukee Elections Commission will seek a formal Postal Service investigation into absentee ballots that city issued and mailed around March 22-23, a commission official said Wednesday.

Those who did not receive their ballot in the mail were able to vote in person on Tuesay.

Patrick Marley, Alison Dirr and Mary Spicuzza of the Milwaukee Journal Sentinel contributed to this report.

Contact Lydia Slattery at 920-426-6710 or lslattery@gannett.com. Contact Nathaniel Shuda at 920-426-6632 or nshuda@gannett.com. Follow them on Twitter at @lydiaslattery and @onwnshuda.