The meeting with Mr. Dimon and other corporate executives was just one of dozens of sessions Mr. Trump has convened with top businesspeople since becoming president. Nearly 300 executives have visited the White House this year, according to a New York Times tabulation, an open-door policy that is a sharp break with the Obama administration and puts corporate chieftains on par with senior lawmakers in the pecking order of who has influence in Washington.

Frank and occasionally confrontational, the conversations have become a defining feature of Mr. Trump’s young presidency, inspiring policy debates and in some instances 180-degree shifts by the president, according to White House officials and executives who have participated in the discussions.

And while some Democrats and other critics complain business leaders are being granted unfettered access to Mr. Trump — who ran as a businessman planning to apply executive principles to Washington’s problems — the White House is unapologetic. The relationship-building is acting as a welcome substitute for a lack of legislative accomplishments, and presidential aides suggest the rapport positions Mr. Trump for future success.

“The whole idea is, do something with all of this communication and feedback,” said Chris Liddell, the president’s assistant for strategic initiatives and a former chief financial officer at Microsoft and General Motors. “And some of that happened in the first hundred days, but we’re really setting ourselves up for the next thousand days.”

Many executives said that they were rarely given face time with President Barack Obama, and that even when they were, they sensed he wasn’t fully engaged. “The feedback from the Obama White House was, ‘We’ll listen to what you have to say, but we know what we’re doing,’” said Kathryn Wylde, president and chief executive of the Partnership for New York City, a business group.