National Highway Traffic Safety Administration chief Mark Rosekind says the agency will act before Labor Day and that the automaker will face enforcement action.
But Rosekind, speaking to reporters after a public hearing on Fiat Chrysler's handling of 23 recalls, wouldn't say more until a comment period closes on July 17.
"There's a pattern that's been going on for some time," Rosekind said, referring to the automaker's conduct. "It's the law; this is what you're supposed to follow."
Rosekind said a number of options for agency action are "on the table," including fines against the company and requiring it to buy back vehicles subject to recall.