CHICAGO (AP) — The candidates for Illinois governor are clashing over taxes during their first televised debate.

Democrat J.B. Pritzker says he wants to change Illinois’ flat tax to a graduated system, in which the highest earners are taxed at a higher rate than middle-class and low-income households. But he won’t say what the new rates should be. He says it should be negotiated with the Legislature.

Republican Gov. Bruce Rauner says Pritzker won’t answer the question because “the truth is so painful.” He says Pritzker “cannot be trusted” on taxes.

Pritzker says Rauner wants to keep an unfair tax system that benefits wealthy people like him.

Also participating in Thursday’s debate are Conservative Party candidate and GOP state Sen. Sam McCann and Libertarian Grayson “Kash” Jackson.

All four said they don’t support taxing services or retirement income.