U.S. Rep. Jesse Jackson Jr. (D-Ill.) said Tuesday he is “deeply sorry” for having “disappointed some supporters” regarding his relationship with a female “social acquaintance.” But the congressman vowed to stay in office in the wake of a Chicago Sun-Times report that a major political fund-raiser has told federal authorities that Jackson directed him to offer former Gov. Rod Blagojevich millions of dollars in campaign cash in return for an appointment for Jackson to the U.S. Senate, to succeed President Obama. The allegation by Oak Brook businessman Raghuveer Nayak regarding fund-raising runs counter to public statements Jackson has made as...