CHICAGO – U.S. Rep. Jesse Jackson Jr., who has given no hint of when he'll return to work four months after taking medical leave, will head back to the Mayo Clinic for a checkup "soon," his father, the Rev. Jesse Jackson, said Sunday.

The Democratic congressman from Illinois was released from the Rochester, Minn., clinic in September after seeking treatment for bipolar disorder and gastrointestinal issues. He has been with his family in Washington since, but has not appeared in public, campaigned beyond a recent robocall or said when he'll return to Capitol Hill. His spokesmen will only say that Jackson remains on the Nov. 6 ballot.

Jackson's father, a prominent civil rights leader, said the congressman will go back to Mayo in the near future, but would not say when or for how long. He said only doctors could determine if he would be able to return home immediately or receive further inpatient treatment.