Bryson's resignation followed a series of traffic incidents in Southern California on June 9. Authorities said Bryson was driving alone in a Lexus near Los Angeles when he struck a vehicle that had stopped for a passing train. He spoke briefly with the three occupants, and then hit their car again as he departed.

The secretary then struck a second car in a nearby city, where he was later found unconscious in his car. Commerce officials said Bryson had not suffered a seizure previously and had "limited recall of the event" involved in the crashes.

In a message to Commerce Department employees, Bryson said their efforts to help American businesses "build our economy and create jobs is more important now than ever." Obama is in the midst of an intense re-election race that will largely be determined by the fate of the economy. Bryson said he would keep supporting Obama in a "personal capacity."