Democratic Rep. Jesse Jackson Jr. is facing mounting calls to provide more details about his unexplained indefinite leave of absence from Congress. The congressman's office says a "serious" medical condition has Jackson undergoing treatment. But officials as high as Sen. Dick Durbin, a Democrat and senior member of the Illinois congressional delegation, are now urging him to clear up what exactly has kept him from work since June 10. Durbin is joined by church leaders, Jackson political challengers and voters in asking for more details and expressing concern about whether they are still being represented by their elected official. Read more: Rep. Jackson facing mounting calls to explain illness, extended absence | Fox News One has to wonder.. "what the hell is he hiding?"