CHICAGO (CBS) – Plans for Congressman Jesse Jackson Jr. to speak to his staffers on Wednesday were abruptly cancelled Tuesday.

CBS 2 Chief Correspondent Jay Levine reports key staffers were surprised with emails and phone calls Tuesday night, telling them the congressman would take part in a conference call with both his local office and his D.C. office at 9 a.m. Chicago time on Wednesday, updating them on his status. Then, just as suddenly, the conference call was cancelled. No explanation was given for the mysterious change of plans.

Jackson has been on medical leave from Congress since June, suffering from bipolar disorder. He was released from his second stay at the Mayo Clinic last week. There’s no word on the congressman’s whereabouts. The entire Jackson family usually gathers in Chicago to celebrate Thanksgiving.

Meantime, Jackson also reportedly is the target of a federal investigation of possible misuse of campaign funds to decorate his home.

His defense attorney, former U.S. Attorney Dan Webb, has been negotiating a plea deal that would call for Jackson to step down for medical reasons, and serve at least some jail time, but keep his federal pension.

Federal prosecutors also reportedly have been investigating whether his wife, Ald. Sandi Jackson (7th), was complicit in any misuse of campaign funds.

Neither Jackson, however, has been charged with any wrongdoing.