The Republican's entry into the 2004 race comes just a year after he was defeated in the GOP primary for the seat eventually won by U.S. Sen. Dick Durbin, D-Ill.
"I was pretty green," Oberweis said of his failed 2002 bid.
Oberweis said he entered the 2002 campaign too late to garner enough support.
This time he has eight months to convince voters he's the right man for the job.
Oberweis said he is against abortion except to save the life of the mother. He pledged to vote against all tax increases and called for caps on damage awards of $500,000 for pain and suffering.
The former teacher, stock broker and investment manager downplayed criticism that he was using his dairy company's first-ever television advertisements -- in which he stars -- to further his political aspirations.
But, he acknowledged that he hopes to receive some political benefit from the company's advertisements for home-delivered milk and ice cream.
"Yeah, I hope so. Of course I do," he told reporters at the Statehouse in Springfield.
Contact Kurt Erickson at at firstname.lastname@example.org