CHICAGO (CBS) — Taxes are one of the central issues in the race for Illinois governor. Democratic nominee J.B. Pritzker admitted he wants to raise taxes on the wealthy, but says he will not reveal his entire tax proposal.

CBS 2’s Political Reporter Derrick Blakley fact checked to see whether Pritzker’s advertised promises add up.

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J.B. Pritzker attacked Illinois flat-rate income taxes in a recent ad.

“When it comes to taxes, Illinois has the most unfair income tax system in America,” Pritzker’s ad states.

Blakley reports that is true. If Illinois doesn’t have the most unfair income tax systems, it is certainly one of the worst. A flat tax is indisputably regressive, meaning while everyone pays the same percentage, 5% of $30,000 bites a lot harder than 5% of $1 million.

“A fair income tax will raise taxes on people like Bruce Rauner and me to support education and help solve the state’s budget problem, while reducing the burden on the middle class,” Pritzker’s ad falsely states. More revenue only helps solve a budget gap if spending is frozen or drops.

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State Representative Steven Reick (R-Woodstock) said, “There’s two words you’ll never hear democrats use in the same sentence, that’s ‘fiscal restraint.’”

Pritzker refuses to reveal his proposed tax rates for specific incomes, so no one knows, for sure, if the middle class will be spared.

State Representative Jim Durkin (R-Western Springs) stated, “Today is a moment of truth for J.B. Pritzker to tell Illinoisans how he intends to raise taxes and how much.”

“He says he wants to negotiate these tax rates with the legislature, which means I’m going to make a deal with Mike Madigan?” said Rep. Keith Wheeler (R-North Aurora).

The Pritzker campaign responded by saying J.B. has been clear about wanting to modernize the tax system so that people, like him and Bruce Rauner, pay more, while the middle class pays less.

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Any more to a graduated tax requires an amendment to the state constitution from the general assembly and then approval from voters.