DETROIT — General Motors, the automaker 61 percent owned by the U.S. Treasury, is facing criticism over its decision to pay $3.5 billion to buy a lender that specializes in auto loans to shoppers with less than top-notch credit.

While GM plans to use its new lending arm to write auto leases and provide a “modest” boost in subprime loans, Sen. Chuck Grassley, R-Iowa, asked the watchdog of the government’s bank-rescue program to investigate the purchase. And a member of a think tank questioned the wisdom of a company that is majority-owned by the government lending money to people with poor credit after a financial crisis was sparked by risky loans.

GM and Fort Worth, Texas-based AmeriCredit Corp. announced the deal Thursday that is intended to help the automaker sell to more customers with damaged credit ratings or who want to lease a new vehicle.

— From wire reports