A potential opportunity created by Barack Obama's election as president in 2008 ironically triggered a series of events that threatened Jackson's political career.

Jackson, then 43, spoke with Blagojevich in fall 2008 about the possibility of being appointed to serve the remaining two years of Obama's vacated U.S. Senate term. Blagojevich was arrested by federal agents the next day and was accused of trying to sell the seat to the highest bidder.

Jackson said he presented only his credentials and polling information that suggested he could win re-election in 2010.

Blagojevich, eventually convicted on multiple corruption charges, started serving a 14-year prison sentence in March.

The House Ethics Committee has been examining allegations that Jackson or one of his associates offered to raise funds for Blagojevich in exchange for the Senate seat.

"In doing so, Rep. Jackson may have violated federal law and House rules concerning the proper use of the member's representational allowance," the statement said.

Jackson has maintained his innocence and pledged to continue to cooperate with authorities. "I did nothing illegal, unethical or inappropriate in that pursuit, and I believe that is what the Ethics Committee will conclude at the end of this process," he said.

Jackson apologized to his constituents in September 2010, after the Chicago Sun-Times reported that a Chicago businessman told federal investigators that Jackson had asked him to pay for a restaurant hostess to fly between Washington and Chicago several times.

He said he was "deeply sorry" that he had "disappointed some supporters."

The newspaper also reported that the businessman, Raghuveer Nayak, told the FBI that Jackson asked him to raise $6 million for Blagojevich in exchange for Obama's vacated Senate seat. The governor ended up appointing former Illinois Attorney General Roland Burris to the Senate post.

Despite the congressional investigation, Jackson decisively won a heated primary for a 10th term in March.

The congressman disappeared from Capitol Hill in May, and in June he explained in a statement released by his staff that he was taking a leave of absence because he was suffering from a "medical condition."

Jackson's wife of 21 years, Sandi Jackson, is a Chicago alderman. The couple met and married during law school. They have two children, Jessica Donatella and Jesse L. Jackson III.