Rep. Jesse Jackson Jr. is suffering from "serious depression -- deep, deep depression," his longtime friend and former U.S. Rep. Patrick Kennedy told CNN Friday, a day after meeting with Jackson at the Mayo Clinic in Rochester, Minnesota.

"Jesse is getting the help he needs and he needs to make that his priority," Kennedy said about the Illinois Democrat who is undergoing inpatient treatment for bipolar depression at the famed facility.

Jackson, 47, has not been on Capitol Hill since late May. In early June, his office released a statement saying that the congressman, who has served in the U.S. House since 1995, was taking a leave of absence because he was suffering from a "medical condition."