Democratic leaders joined colleagues and constituents Wednesday in calling for Jackson Jr. to offer a public explanation as soon as possible.
Congressman Jackson started his leave on June 10, but he waited two weeks to make it public.
The mystery surrounding Jesse Jackson Jr.'s illness could not have happened at a worse time for his father. The veteran civil rights leader is hosting the annual Rainbow PUSH coalition conference in Chicago.
For the first time in the Rainbow PUSH convention's 41 years, Rev. Jesse Jackson tried to avoid cameras and reporters. He apparently did not want to hear questions about his son, Rep. Jesse Jackson Jr., who has taken an extended leave from Congress without explaining the nature of his illness.
As Jackson Sr. tried to leave the Rainbow PUSH luncheon through the ballroom kitchen Wednesday afternoon, ABC7 intercepted him to ask about the non-stop rumors surrounding his son's health.
"I should not have to dignify rumors," said Rev. Jackson. "It's not fair. His medical treatment is a private matter by his doctors, his family. At the appropriate time you will hear as you should."
Meanwhile, in Washington, House Minority Whip Steny Hoyer urged Jackson, who stands for re-election in November, to provide voters more detailed information.
"I think Congressman Jackson and his office and his family would be well advised to advise the constituents of his condition," Hoyer said. "He's obviously facing a health problem."
But Democratic minority leader Nancy Pelosi advised patience.
"Our prayers are with his family. The timing is not related to our curiosity but his healthcare needs," said Pelosi.
The congressman's wife, Alderman Sandi Jackson, told the Chicago Tribune Wednesday she was "hopeful" doctors would release details of the congressman's condition "soon". She claimed to be in constant contact with her husband's medical team.
"I'm asking the media, I'm asking the Democrats to back off of this young man," said former Illinois U.S. Senator Roland Burris.
Burris said his fellow Democrats should end their calls for Jackson to come forward and blamed the news media for trying to bring down the congressman.
"The media's driving it," said Burris. "They drove the mess with me."
The Rainbow PUSH conference continues through Saturday.