MT. PROSPECT, Ill. (CBS) — For the first time this year, all four of the Republican candidates for governor were on the same stage, and there were some fireworks.

WBBM Newsradio Political Editor Craig Dellimore reports the other three GOP hopefuls had billionaire Bruce Rauner in their sights from the start of the forum focusing on business concerns.

READ MORE: Mobile City Hall Bringing City Services To Little Village Tuesday

While most questions focused on business and financial concerns in Illinois, Rauner’s purported ties to convicted influence peddler Stuart Levine came up, and state Sen. Kirk Dillard pounced.

“Mr. Rauner needs to … answer why he paid Stuart Levine – the mastermind of the Blagojevich corruption ring – $25,000 a month,” Dillard said.

According to news reports, Levine was getting $25,000 a month in 2003 to seek government business for a company that had been acquired by an investment firm owned in part by Rauner.

Rauner said he didn’t even know Levine, who was a key figure in the federal investigation that took down former Gov. Rod Blagojevich, and political fundraiser Antoin “Tony” Rekzo.

“He [Levine] had a company that was a subsidiary of a company that we had a minority investment in, along with other venture capital firms. I didn’t know it. I wasn’t on the board. Never interacted with him. Don’t know the guy,” he said.

READ MORE: Police Release Video Of Suspects Wanted In Death Of 18-Year-Old Azul De La Garza

State Sen. Bill Brady was incredulous.

“Mr. Rauner, I just find it hard to believe that you presented yourself in front of a board, and didn’t know who Stuart Levine was, the most notorious guy,” he said.

Rauner said the other candidates were attacking him because he’s leading in the polls.

“The reason I’m being attacked is I’ve got a message that’s resonating with the voters, and we’re winning the race,”

State Treasurer Dan Rutherford tried to stay above the fray, but snapped later when Rauner criticized him, while also saying he’s the only GOP candidate not to take money from government labor unions.

“Dan, you’ve taken a lot, more than $100,000,” Rauner said.

MORE NEWS: Chicago Police Officers Refusing To Report Vaccine Status Expected To Protest Outside Police Headquarters Tuesday

“That is not correct, Bruce Rauner,” he said. “Don’t do that. That is not correct. I pulled my D-2s (campaign finance disclosure forms), you have no right to put out false information on me.”