Duffy also said he would cut DEI programs at the agency and create federal rules for self-driving cars instead of leaving that to a patchwork of state regulations, a key priority of Tesla CEO Elon Musk, who is running Trump’s government efficiency effort.

Appearing alongside President Trump and Defense Secretary Pete Hegseth at a White House briefing, Duffy outlined the “whole of government response” to the crash and committed to “get to the bottom of this investigation — not in three years, not in four years, but as quickly as possible.”

Mr. Duffy, a former congressman who had appeared on track to sail through with little opposition, overcame a last-minute swell of Democratic anger over the White House’s sweeping funding freeze.