CHICAGO — Battling mental illness and personal financial troubles, Rep. Jesse L. Jackson Jr. (D-Ill.) is a heavy favorite for reelection Nov. 6 despite a surreal campaign from which he has been absent for almost four months. Jackson, 47, who disclosed this summer that he has bipolar depression and has undergone weeks of hospitalization, is convalescing in Washington and meeting occasionally with aides. He has been absent from the House of Representatives since June 8. Whether he will campaign at all is in question. His reelection bid is being led by his wife, Sandi Jackson, who turned down interview requests....