Millionaire investment banker-turned-inner-city schoolteacher Jack Ryan (search) is leading the Republican pack of contenders seeking the nomination for the Illinois U.S. Senate seat being vacated by one-term Sen. Peter Fitzgerald.

But during his absence in a Wednesday night televised debate, his GOP rivals raised questions about his failed marriage. They called on him to unseal his divorce records.

"If you want to represent your party ... and take its nomination ... I think you have to be prepared to open up your life and do these things," said Republican candidate Steve Rauschenberger (search).

Ryan and his wife, Jeri, divorced five years ago. That record is open but documents regarding the custody of their now 9-year-old son are sealed.

"They're sealed for the protection of my son ... and he's the most important thing in my life ... and nothing is ever going to jeopardize his future," Ryan said.

Divorce has also been a thorny issue for the Democratic candidates in the race.

Another candidate, Blair Hull, (search) has also been questioned about his relationship with his wife. Hull's wife claims that he struck her, among other things, and Hull called it a "contentious and messy divorce … that was financially motivated."

Click here for a report by Fox News' Steve Brown.