A day after Illinois Rep. Jesse Jackson Jr. resigned from Congress, speculation swirled over who might replace the 10-term Democrat re-elected to office just two weeks ago.
Jackson on Wednesday sent his resignation letter to House Speaker John Boehner, citing his ongoing treatment for bipolar disorder and admitting "my share of mistakes," while confirming publicly for the first time that he's the subject of a federal probe. He said he is cooperating with investigators.
"For seventeen years I have given 100 percent of my time, energy and life to public service," Jackson wrote. "However, over the past several months, as my health has deteriorated, my ability to serve the constituents of my district has continued to diminish. I am aware of the ongoing federal investigation into my activities and I am doing my best to address the situation responsibly, cooperate with the investigators, and accept responsibility for my mistakes, for they are my mistakes and mine alone."
Jackson, the 47-year-old son of civil rights leader Jesse Jackson, defeated Republican challenger Brian Woodworth this month by 40 percentage points, despite not campaigning for re-election.
Jackson will be replaced in a special election in the state's 2nd Congressional District. Illinois Gov. Pat Quinn, a Democrat, said Wednesday he will announce a schedule within five days for a special election. He said he planned to set both a primary and a general election.
While a clear successor to Jackson is unknown, several names have been floated around Chicago's political circles. Prominent Chicago attorney Sam Adam Jr., a onetime attorney for Blagojevich and R&B singer R. Kelly, said he'd be interested. Other names circulating are Chicago Aldermen Sandi Jackson and Anthony Beale and Cook County Board President Toni Preckwinkle.
Another possible contender is former Rep. Debbie Halvorson, who challenged Jackson in this year's Democratic primary but lost.
The Chicago Sun-Times reported that Todd Stroger, former Cook County Board president, is also interested in the seat. Stroger, whose two former aides are currently facing public corruption trials, told the newspaper that he is giving it serious consideration after receiving calls from listeners on his talk radio show.
Political consultant Delmarie Cobb, who was once Jackson’s press secretary, reportedly likened the race to replace her former boss to the "Wild Wild West."
"It’s going to be the Wild Wild West, unfortunately, because you're going to have about 12 people – at my last count – who are going to throw their names in the race," Cobb told Chicago station WBBM-TV.
Jackson's fate is also uncertain.
Federal authorities are reportedly investigating Jackson's possible misuse of campaign funds and the House Ethics Committee is investigating his dealings with imprisoned ex-Illinois Gov. Rod Blagojevich. It was unclear how the committee would proceed following Jackson's resignation. The committee could still decide to release a final report on him but it no longer has the power to punish Jackson.
Jackson was never charged with wrongdoing, and his attorneys offered few details of the reported probe into misuse of campaign funds.
"Mr. Jackson is cooperating with the investigation. We hope to negotiate a fair resolution of the matter but the process could take several months," according to a statement from Jackson's attorneys, including former U.S. Attorney in Chicago Dan Webb.
"During that time, we will have no further comment and urge you to give Mr. Jackson the privacy he needs to heal and handle these issues responsibly."
Experts said Jackson's resignation and confirmation of the federal investigation signaled more details would likely follow.
"I think it won't be too long before we hear an announcement of a plea agreement," said Bruce Reinhart, a white-collar defense lawyer in West Palm Beach, Fla., who was a federal prosecutor for 19 years. "The government doesn't like people who are going to plead guilty to abusing public office to remain in a position of public trust. ... Resignation would be a significant bargaining chip for Congressman Jackson in order to get a better deal from the government."
Late Wednesday the longtime Chicago congressman's father, the Rev. Jesse Jackson Sr., told reporters his son resigned because he didn't believe he could continue to serve effectively while also trying to get well.
"He made the decision to choose his health," Jackson said.
Jackson Jr. left Washington unexpectedly in June, leaving fellow Capitol Hill lawmakers, his staff and voters to learn several weeks later that he was being treated for a bipolar disorder.
His father also told reporters there is no way of knowing how long it will take for his son to recover from what he characterized as an "internal unresolved challenge."
"It's not the kind of illness you can put a timetable on," Jackson said, adding that he is confident his son "will get well in time."
Jackson first took office in 1995 after winning a special election in a Democratic district made up of South Side Chicago neighborhoods, several southern suburbs and rural areas.
He began his career in Washington with a star power and pedigree that set him apart from his hundreds of other House colleagues. But despite high expectations, Jackson largely went unnoticed as a policymaker.
Fellow congressman said Jackson's resignation not been an easy decision.
Rep. Bobby Rush, a fellow Chicago Democrat, told reporters that he spoke to a melancholy Jackson on the phone early Wednesday morning -- hours before he submitted his resignation.
"He sounded very sorrowful -- in so much pain ... that he wouldn't be able to serve in Congress anymore," Rush said.
Fox News' Chad Pergram and the Associated Press contributed to this report.