Toni Preckwinkle’s chief of staff has resigned over allegations of “inappropriate and disrespectful behavior,” the Cook County Board president said in a statement released Wednesday — a day before Preckwinkle planned to announce her bid for mayor.

Preckwinkle said she learned of the allegation Friday regarding John Keller, a longtime aide and associate of hers. After confirming the charge, she ousted him from his post, which he held since January 2017.

“As President of the Cook County Board of Commissioners and as a woman, it is important to me to foster a workplace that is respectful, where all people are treated with dignity,” the statement said. “I have always had zero tolerance for inappropriate and disrespectful behavior. On Friday, I became aware of an allegation that my Chief of Staff, John Keller, had engaged in inappropriate behavior on his personal time. The allegation was corroborated. I confronted Mr. Keller; he did not deny the allegation. Yesterday, I demanded and received his immediate resignation.”

Keller could not be reached for comment.

The timing of the abrupt dismissal, which sources said was related to a “#MeToo” complaint, raised eyebrows. Preckwinkle is scheduled to announce her campaign for mayor at a 3 p.m. press conference Thursday at the Chicago Lake Shore Hotel.

“Why did Preckwinkle wait this long to take action?” asked a top Dem political source.

Sneed is told the allegation stemmed from Keller’s time working for the campaign of Marie Newman, who lost a bid to unseat U.S. Rep. Dan Lipinski, D-Ill., in the March Democratic primary.

The rumors of Keller’s behavior, which involved a woman working on Newman’s campaign, had been floating since then, according to another Dem source.

“There was a large contingent of people working for Newman who were huge supporters of ‘Chuy,'” —  former Cook County Commissioner Jesus “Chuy” Garcia, the source said. Garcia, who is the frontrunner to win the congressional seat now held by retiring U.S. Rep. Luis Gutierrez, was once close with Preckwinkle — but no longer. He is expected to announce a mayoral bid soon.

The big question: did Garcia’s supporters force Preckwinkle’s hand?