He said that, should he run, he would offer himself as a “conservative with a big heart.”

To that end, he said, he would do nothing to curtail benefits for senior citizens, whom he called the “lifeblood of this country.” But he suggested that his biggest objection to Representative Paul D. Ryan’s deficit reduction plan — which has alarmed seniors on Medicaid — was not its substance but what he saw as poor strategy by Mr. Ryan, a Wisconsin Republican, in rolling it out.

“As a poker player, he shouldn’t have put forth such an early plan,” Mr. Trump said. “Anybody who touches Medicare,” he added, “is in tremendous trouble politically. We, the Republicans, have an election to win.”

Mr. Trump, who faces scrutiny from Republicans over his conservative credentials, said he no longer supported two proposals he put forth in 1999, when he last considered running for president: a one-time tax of 14.25 percent on the wealthiest Americans and a single-payer health care program.

“We had a much different country when I proposed those two things,” he said.

Mr. Trump spoke knowledgably — and harshly — about Mr. Obama’s health care overhaul and America’s trade policies with China. But at times he betrayed a lack of engagement closer to home, incorrectly stating that only one member of the New York City Council was a Republican. (There are five.)

Mr. Trump, 64, repeatedly found ways to weave the topic of his wealth, and its reach, into the conversation. “Look at that,” he interrupted, pointing to a giant white plane hovering outside the room’s windows. “That’s my plane. How beautiful is that?”

He also announced that he had just bought a Boeing 757 from Paul G. Allen, one of the founders of Microsoft, and was having it refitted to his specifications. “I was going to buy a 737,” he explained, “then I heard about this one.”

Yet Mr. Trump emphasized that he was ready to walk away from much of his life to mount a bid for the presidency.