Rev. Jesse Jackson says his son, the Illinois congressman, is "slowly regaining his strength" but offered no other details on why his son has been on medical leave since June 10th. "We're with him and we hope that he'll be fully restored to his health," Rev. Jesse Jackson told [NBC Chicago's Stefan Holt.](http://www.nbcchicago.com/blogs/ward-room/Rev-Jackson-Mum-Jackson-Jr-Exh...) "Right now he's going through a tremendous challenge." When asked exactly what's wrong with the congressman, Rev. Jesse Jackson told NBC Chicago it's "inappropriate" to disclose details. "The crisis is deeper than we thought it was. But the good news is, he's under good supervision. He's been in touch with his mother and his wife, and he's on the rebound. To me, that's the good news about it all," Rev. Jesse Jackson, the congressman's father, told NPR's David Schaper. Jackson's congressional colleagues are now pressuring Rep. Jackson's office to release more information. "As a public official ... there reaches a point when you have a responsibility to tell people what you're facing and how things are going," Sen. Dick Durbin, the senior Democrat in Illinois, also told reporters yesterday. Rep. Luis Gutierrez, D-Ill. told NPR "the people of Illinois deserve it. If he's going to stand for re-election, you guys [reporters] are going to demand it." "I think that he has a responsibility to give us more information, and I'm not demanding that information, but I think the people of his congressional district deserve it," Gutierrez went on to say.