"Mr. Viola has informed President Trump that he will be unable to accept his nomination to serve as secretary of the Army as the challenges of separating Mr. Viola from the organizations that he has built over the last thirty-five years have proven insurmountable," a statement from Viola's team on Friday evening said.
"I am deeply honored to have been considered for this post, and appreciate the confidence President Trump showed in me," Viola said. "I offer my continued support for President Trump and his administration, and look forward to re-doubling my efforts to support the Army and its veterans as a private citizen."
Viola is a billionaire from New York who owns the Florida Panthers, a hockey team. He graduated from West Point and served in the 101st Airborne, becoming a soldier in the US Army Reserve after his active duty. He founded several companies, including one high-frequency trading firm, where he earned his billions.
Were he to go through the confirmation process, his finances would have been subject to Senate scrutiny and disclosure requirements.
Viola is one of a handful of billionaires Trump has nominated to serve in his administration who have faced intense pressure over potential conflicts of interest. Trump himself has received similar scrutiny and criticism, although as President, he does not face the kind of disclosure rules as Senate-confirmable positions.
If confirmed by the Senate, Viola would have served as Army secretary under Defense Secretary James Mattis.
CNN has reported that Mattis was unhappy with Trump's choice of Viola, with several sources saying before last month's inauguration that Trump made the selection without consulting Mattis. One source said Mattis was so angry, he threatened to quit if Trump made more Pentagon appointments without consulting him.
Sean Spicer, now the White House press secretary, disputed such reports at the time, saying on Twitter there was a "great transition" underway at the Defense Department, CNN reported.
Two sources said Mattis preferred Michele Flournoy for Army secretary. She previously served in the Obama administration's Department of Defense.
In a statement, Capt. Jeff Davis, a Pentagon spokesperson, said Mattis is "disappointed but understands and respects Mr. Viola's decision."
"The Secretary is confident that Mr. Viola will remain a stalwart supporter of America's soldiers," Capt. Davis said. "The Secretary will recommend to the President another candidate soon."