If " [m]ore than nine out of ten people in Illinois think that Gov. Rod Blagojevich should resign", then that majority is going to be disappointed.
While Blago may be an obvious criminal, he is also arrogant and thinks he can beat this. But neither of these explain why he won't resign.
Blago won't resign because doing so will be to admit that the charges against him are correct. His lawyer won't let him resign. The correct thing to do will be for the Illinois legislature to impeach him. He'll be able so say that he did not quit on his own, and will then be able to fight his criminal charges as well as he can.