Eyewitness News Political Reporter Charles Thomas was one of the moderators at the forum, which was the first time all four Republican candidates have appeared together this year. And for three, their first chance to confront the controversial, self-described front runner Bruce Rauner.
"The reason I'm being attacked is I've got a message that's resonating with the voters and we're winning the race," said Rauner.
The tone changed when Senator Kirk Dillard was asked about his comments this week that multi-millionaire businessman Bruce Rauner is "unelectable."
"There will be questions about how he uses his money, how he uses his influence, how he's made his money," said Sen. Dillard.
Senator Bill Brady piled on, repeating allegations that Rauner-- who has already spent hundreds of thousands of dollars on television advertising-- clouted his daughter into a CPS magnet school and that a Rauner subsidiary that did business with the teacher retirement system fund hired TRS board member Stuart Levine, the political fixer in the Blagojevich scandal.
"You can't avoid it. You can't advertise your way out of it, Bruce," said Sen. Brady.
"To say that I somehow used or bribed him to get Teacher's business? Oh my goodness, is pure baloney!" said Rauner.
Later, Rauner cited Brady's political failures.
"You've been running for governor for nine years. You've lost twice. I helped you raise millions of dollars the last time. You've lost to the worst governor in America," said Rauner.
Treasurer Dan Rutherford-- the only current statewide office holder-- tried to remain positive.
"I'm the only guy that's been able to win in Illinois," said Rutherford.
But after Rauner said Rutherford took union money and was AWOL during the pension reform debate, the treasurer reacted angrily.
"Do not put out false information about me, Mr. Rauner. OK, we'll have time during the race to deal with that," said Rutherford.
Mr. Rauner's handlers led him away from the event without letting the candidate answer any more questions. It is unclear how many more such forums Rauner will attend.
He initially said he would not participate in Thursday's event in Mt. Prospect.