WASHINGTON U.S. Commerce Secretary John Bryson, under investigation for his role in two car crashes on the same day this month, said on Thursday he was resigning to prevent distractions at the department he led for less than a year.
Police found Bryson unconscious behind the wheel of his Lexus on June 9 after he crashed into one car twice, left the scene of the accident and collided with another vehicle.
He was cited on suspicion of a felony hit-and-run in the first crash, but so far no charges have been filed.
Police said on Thursday they were awaiting results of toxicology tests and the Commerce Department said initial tests showed he had a seizure.
"I have concluded that the seizure I suffered on June 9th could be a distraction from my performance as secretary and that our country would be better served by a change in leadership at the department," Bryson said in letter on Wednesday to President Barack Obama.
Police said Bryson, a 68-year-old former energy company executive brought into the administration to reach out to business, was alone at the time and there was no indication that alcohol or drugs played a role in the collisions.
He was treated at the scene, regained consciousness and was admitted to a local hospital. Passengers in the other cars had no major injuries, police said.
Commerce Department officials could not say whether the seizure happened before or after the accidents.
Amid speculation about his health and future in the administration, Bryson took a leave of absence to undergo medical tests and evaluation.
A preliminary diagnosis found Bryson had a "complex partial seizure" but further testing and evaluation are ongoing, a Commerce Department official said.
Obama met with Bryson on Thursday afternoon to thank him for his service.
"As secretary, John fought tirelessly for our nation's businesses and workers, helping to bolster our exports and promote American manufacturing and products at home and abroad," the president said in a statement.
In March, Bryson led a five-day business mission to India, a market the Obama administration has targeted for increased exports. Along with U.S. Trade Representative Ron Kirk, he co-chaired a high-level joint commission with China to tackle difficult trade irritants.
Bryson helped roll out "Brand USA," a new public-private partnership to attract more visitors to the United States. He co-chaired the White House office on manufacturing policy and said his top priority was to help more American businesses "build it here and sell it everywhere."
The president said Deputy Commerce Secretary Rebecca Blank, who has served as acting secretary since last week, would continue in that position. That reprises a role she served for three months last year, after former Commerce Secretary Gary Locke became the U.S. ambassador to China.
White House spokesman Jay Carney refused to rule out the possibility that Obama, with less than five months before the November presidential election, would nominate someone else for the Commerce secretary job.
"But the president has a lot of confidence in Dr. Blank. She has served in this position already and did it quite well," Carney said. "If we have a personnel announcement to make beyond that, we'll let you know."
Business officials, speaking on condition they not be identified, said they had been unaware of any health issues, but noted Bryson had a ponderous speaking style and sometimes in private meetings seemed to struggle for words.
At both his confirmation hearing and later appearances before Congress, he sometimes stumbled when explaining administration policy positions, a mistake many officials can make when new to the job.
Bryson is a former chief executive of Edison International, a public utility holding company headquartered in Rosemead, California. He had served as Obama's secretary of commerce since October 2011.