CHICAGO -- U.S. Rep. Jesse Jackson Jr. was back at the Mayo Clinic for an evaluation Tuesday and possibly a longer stay, nearly two months after being released for treatment of bipolar disorder at the Minnesota hospital, his father said Tuesday.

"I don't know how long he's going to be there," his father, civil rights leader Rev. Jesse Jackson, told The Associated Press.

The hospital confirmed Tuesday that Jackson was back at the facility in Rochester, Minn., for a follow-up evaluation "to ensure he is on the path to properly manage his health." The statement did not say much else.

His father said his son was at the clinic for a doctor's visit, and a family spokesman said he would issue a statement after the evaluation.

The congressmen quietly went on medical leave in June, and his office released scant details until the Mayo Clinic confirmed nearly two months later that he had been treated for bipolar disorder and gastrointestinal issues.

Even though Jackson is facing re-election in November, he has made no public appearances since then. The only campaigning he's done has been a recorded robocall to voters over the weekend where he asked for patience. But his wife, Chicago City Councilwoman Sandi Jackson, his father and two fellow Democratic Illinois congressmen who visited him Monday have all said they've encouraged him to take his time in coming back to work or the campaign.

One of those congressmen, U.S. Rep. Bobby Rush, said Jackson was preparing for a long stay at Mayo.

Questions about Jackson's health – and the timing of his medical leave – have rippled beyond his Chicago-area congressional district. Neither his congressional spokesman nor family members have been forthcoming with updates, saying little beyond that he's been seeing doctors daily since he was released from Mayo in September.

Jackson, 47, remains under a House Ethics Committee investigation about ties to imprisoned former Illinois Gov. Rod Blagojevich. And his medical leave wasn't announced until days after a former Jackson fundraiser connected to the Blagojevich investigation was arrested on unrelated federal medical fraud charges. Since then, the Chicago Sun-Times has reported inklings of another federal investigation over congressional finance.

When he was first admitted, the Mayo Clinic disclosed that Jackson was suffering from Bipolar II, which is defined as periodic episodes of depression and hypomania, a less serious form of mania. He was released and returned to his family's Washington home last month.

Soon after his return, his family put their Washington condo on the market for $2.5 million, in part they said to help pay for medical costs. They later took it off public listings because of the visitors coming to the home and fear of safety, his wife has said.

Jackson, who first took office in 1995 and captured every election in a strong majority since then, faces two little-know challengers on the ballot. He's widely expected to win re-election.

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Earlier on HuffPost:

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  • Jesse Jackson Jr.

    FILE - In this March 21, 2010 file photo, Rep. Jesse Jackson, Jr., D-Ill., uses his PDA to photograph demonstrators outside on the U.S. Capitol as the House prepares to vote on health care reform in Washington. When Jackson disappeared on a mysterious medical leave in June 2012, it took weeks for anyone in Washington to notice. Jackson has never lived up to the high expectations on the national stage.

  • Jesse Jackson, Jr.

    FILE - In this Jan. 5, 2011 file photo, Rep. Jesse Jackson, Jr., D-Ill., is pictured before a ceremonial swearing in of the Congressional Black Caucus on Capitol Hill in Washington.

  • Jesse Jackson Jr.

    FILE - In this May 16, 2011 file photo, U.S. Rep. Jesse Jackson Jr. attends ceremonies for Chicago Mayor-elect Rahm Emanuel in Chicago. (AP Photo/Charles Rex Arbogast, File)

  • Jesse Jackson Jr.

    FILE - In this Tuesday, March 20, 2012 file photo, U.S. Rep. Jesse Jackson Jr., D-Ill., thanks supporters at his election night party in Chicago. Jackson's office announced Monday, June 25, 2012 in a news release that the congressman has been on a medical leave of absence since June 10 and is being treated for exhaustion. (AP Photo/M. Spencer Green, File)

  • Jesse Jackson Jr., Sandi Jackson

    U.S. Rep. Jesse Jackson Jr., D-Ill., and his wife Chicago Alderman Sandi Jackson, thank family members at his election night party Tuesday, March 20, 2012, in Chicago after his Democratic primary win over challenger, former Rep. Debbie Halvorson, in the Illinois' 2nd District. (AP Photo/M. Spencer Green)

  • Jesse Jackson Jr., Sandi Jackson

    U.S. Rep. Jesse Jackson Jr., D-Ill., and his wife Chicago Alderman Sandi Jackson, embrace at his election night party Tuesday, March 20, 2012, in Chicago after his Democratic primary win over challenger, former Rep. Debbie Halvorson, in the Illinois' 2nd District. (AP Photo/M. Spencer Green)

  • Timothy Geithner, Jesse Jackson Jr.

    Treasury Secretary Timothy Geithner, right, declines an offer by U.S. Rep Jesse Jackson Jr., D-Ill., to talk to reporters during a tour of the Ford Motor Company Stamping Plant in Chicago Heights, Ill., Wednesday, April 4, 2012. (AP Photo/Charles Rex Arbogast)

  • U.S. Rep. Jesse Jackson Jr., Sandi Jackson

    U.S. Rep. Jesse Jackson Jr. and his wife, Chicago Alderman Sandi Jackson, ask each other for their support and votes as they arrive at a polling station for early voting, Friday, March 9, 2012, in Chicago. (AP Photo/M. Spencer Green)