A commercial driver’s license (CDL) bribery scandal has forced Illinois Governor George Ryan, a Republican, to give up running for a second term.

To date, some 38 people in the state have been convicted under federal law for issuing CDLs to unqualified drivers in exchange for cash bribes to Ryan’s campaign fund. Ryan, who was Illinois’ secretary of state at the time, denied any knowledge of the bribes-for-license scheme and has not been charged with any crime.

The bribes – which totaled some $170,000, according to prosecutors – were used as campaign contributions or to buy tickets to Ryan fundraising events. Although the governor maintained he had no knowledge of the scheme, several of his close associates were convicted, including Dean Bauer, the secretary of state inspector general at the time and a friend of Ryan’s since boyhood.