Jason Plummer is refusing to turn over the information weeks after State Senator Bill Brady, his Republican running mate for governor, gave in on his earlier refusal to release tax records.
Plummer is the only one of four major party candidates for governor or lieutenant governor who refuses to allow any inspection his tax return.
Brady sparked controversy late last month after he allowed reporters a glimpse of his last few returns.
Plummer, it appears, is taking no chances.
"When these candidates play peek-a-boo, or not at all, with their tax returns, I think there's legitimate questions to be asked," said Quinn.
In response to a question, the governor opened a full bore attack on the Republicans running for the state's top executive offices.
He was asked if thought Plummer was hiding something, Quinn said: "I think that's a natural conclusion - I don't think there's any question about it, you know, when you don't disclose your tax returns and you're running for lieutenant governor of Illinois."
We've been told the 27-year-old Plummer worked for the Edwardsville lumber company owned by his parents. The state board of elections reports he financed his primary campaign with over a million dollars in loans from the business, his family and himself. He will not provide proof and origin of income last year.
One of Plummer's campaign ads has included a pledge to make government more transparent: "One candidate will push for real campaign reform, requiring complete government transparency."
Plummer was unavailable for comment Friday. In a statement earlier this week he maintained that "releasing tax returns is often used as a political distraction by those who cannot answer the real issues that voters care about."
Brady initially refused to release his return, but he relented under pressure. He allowed reporters three hours to view, but not copy, the documents. They revealed that homebuilder Brady had not paid taxes in two years. He claimed his lack of tax payments was because of business losses.
"If you've got a taxpayer salary, if you have taxpayer paid health insurance, and you don't pay one penny in taxes... It isn't right," said Quinn.
A Brady spokeswoman Friday afternoon called the governor's comments "political gamesmanship."
Earlier this week, a campaign spokesman said Plummer did file a return, but he would not say if the young man paid any taxes.
There has been absolutely no give by Plummer on this issue, and it seems he is hoping that the controversy fades with time.
However, it seems likely that the Quinn campaign will revive the issue in its campaign commercials later this year.