Jackson is good friends with Republican Congressman Mark Kirk and "they have a great relationship," according to workers for Jackson who wish to remain unnamed.
Though the two men are from different political parties, they have worked together over the years. In fact, Kirk has even attended a Jackson fundraiser.
Jackson insiders compare Jesse Jr's confidence in Kirk to the same way he felt for his former colleague Republican Congressman Henry Hyde.
"If Hyde had asked" -- which he didn't -- "Jesse would have endorsed him," says one of Jackson's staffers.
As for Jackson's summer plans, the same staffer says "he's been told to be available June 3rd if called."
June 3rd is the start of the Blagojevich federal trial, unless SCOTUS grants a trial delay. Jackson testimony may make commuting back and forth to Washington a bit tough for the Congressman ... and others on the witness list.