Who is “Senate Candidate Number 5”?

From the affidavit against Blagojevich:

According to the affidavit, one candidate for the senate seat, identified as Senate Candidate 5, promised to “raise money” for Blagojevich. The governor described, in a recorded call, an earlier approach by an associate of Senate Candidate 5.

“We were approached ‘pay to play.’ That, you know he’d raise me 500 grand. An emissary came. Then the other guy would raise a million, if I made him (Senate Candidate 5) a Senator,” Blagojevich was quoted as saying.

Is it Rep. Jesse Jackson, Jr. or Obama’s kingmaker and outgoing Illinois Senate president Emil Jones, Jr., who expressed interest in the seat this past Sunday? If so, it sounds like Blago might have been heeding the advice/threats from Rep. Bobby Rush.

Enquiring minds want to know …