The U.S. should replace dollar bills with dollar coins, a watchdog said, a move that could be unpopular with the public but ultimately save the government money.

“We continue to believe that the government would receive a financial benefit from making the replacement,” Lorelei St. James, a director at the nonpartisan Government Accountability Office, said in remarks prepared for a Congressional hearing scheduled for Thursday.

Mining and metals companies, mass transit agencies, vending machine manufacturers and other groups favor a switch to coins. They are pitted against the company that makes the paper for U.S. currency, Crane & Co., and broad public opinion in favor of keeping the greenback. Both sides have allies in Congress.