The New York Times reports:
During the primaries, the group briefing him for debates was small and closely held. By the weekend before the debate on Monday at Hofstra University, there were nearly a dozen people preparing Mr. Trump, including the retired Army generals Michael Flynn and Keith Kellogg, neither of whom has experience in presidential debates.
There were early efforts to run a more standard form of general election debate-prep camp, led by Roger Ailes, the ousted Fox News chief, at Mr. Trump’s golf course in Bedminster, N.J. But Mr. Trump found it hard to focus during those meetings, according to multiple people briefed on the process who requested anonymity to discuss internal deliberations. That left Mr. Ailes, who at the time was deeply distracted by his removal from Fox and the news media reports surrounding it, discussing his own problems as well as recounting political war stories, according to two people present for the sessions.
Rudolph W. Giuliani, the former New York City mayor and a friend of Mr. Trump’s who has been traveling with him extensively, took over much of the preparation efforts by the end. But with Mr. Trump receiving so much conflicting advice in those sessions, he absorbed little of it.
The team had primed Mr. Trump to look for roughly a dozen key phrases and expressions Mrs. Clinton uses when she is uncertain or uncomfortable, but he did not seem to pay attention during the practice sessions, one aide said, and failed to home in on her vulnerabilities during the debate.
“It clearly looked like he ran out of gas after 30 minutes, and that came through loud and clear,” said Scott Reed, the senior political strategist for the U.S. Chamber of Commerce, who has not supported Mr. Trump.