CHICAGO (CBS) — Opponents of Congressman Jesse Jackson Jr. are turning up the heat as prospects increase that the nine-term congressman may not return to work or campaign prior to the Nov. 6 election.

It may be the local version of Clint Eastwood’s empty chair discussion with President Obama, CBS 2 Chief Correspondent Jay Levine reports.

Jackson’s challengers in the 2nd Congressional District are finding it’s hard to hit what you can’t see.

Jackson has been out of the public eye since his office announced over the summer he was being treated for bipolar depression and other medical problems. He was released from the Mayo Clinic last month.

Brian Woodworth is the Kankakee College professor, a white Republican, running against Jackson in the mostly minority district.

“If he’s unable to campaign that does have a reflection: Is he going to be a representative after the election?” Woodworth says.

Supporters of independent candidate Marcus Lewis, a Matteson mail handler, demonstrated outside Jackson’s south suburban congressional office Friday.

“There’s no sense of voters voting for somebody they know will never take oath of office,” Lewis said.

While Jackson may not be gravely ill, sources tell CBS 2 his physical and emotional issues are serious. And they do raise questions about whether he’ll ever return to Congress. Still, most aren’t as cynical as his challengers.

“If he’s there for 20 years in the House, he needs one more term,” Lewis says. “And at the age of 50 he gets 100 percent of his pension and lifetime health care. And so he’s just trying simply to get elected.”

Jackson won’t actually qualify for that 20-year pension until December 2015. That means he’d have to serve another full term and face the voters again before he’d get to retire with full salary and medical benefits.