Jackson's departure from the clinic comes amid reports that he is the target of a federal investigation over using campaign funds to decorate his home. Jackson has reportedly also retained an attorney to negotiate a plea deal with federal officials. According to multiple outlets, the tentative deal would include resigning from Congress — citing health reasons — and paying back some of the money Jackson allegedly spent.

Jackson's office has refused to comment on the reported deal. Sen. Dick DurbinRichard (Dick) Joseph DurbinSunday shows preview: Lawmakers gear up for Senate impeachment trial Parnas pressure grows on Senate GOP Overnight Defense: Book says Trump called military leaders 'dopes and babies' | House reinvites Pompeo for Iran hearing | Dems urge Esper to reject border wall funding request MORE (D-Ill.) and Chicago Mayor Rahm Emanuel, formerly President Obama's chief of staff, have both called on the Illinois congressman to release more details about the investigation and whether he is fit to continue to serve in 2013. 

Jackson won reelection to his district last week with 63 percent of the vote despite his extended absence.