The private equity titan is a longtime Republican donor who has known the president-elect for years. Mr. Trump and his wife, Melania, were among the guests to the Blackstone chief’s famous 60th birthday party in 2007.

Mr. Schwarzman was not a vocal supporter or fund-raiser for Mr. Trump. Since the election, however, he has embraced the notion that the president-elect’s promise to pull back financial regulations and cut taxes will supercharge the economy.

In public and in private, Mr. Schwarzman has lately said that he is “excited” about the potential for economic growth in a Trump administration.

“The business community now becomes front and center,” he said at a recent Wall Street Journal conference.

At the conference, Mr. Schwarzman listed a number of likely changes under Mr. Trump, including a loosening of lending regulations, a lowering of the corporate tax rate from its current 35 percent level, and a return of the more than a trillion dollars American companies currently hold abroad to avoid United States taxes.

“There are going to be so many of these changes that I think what’s going to happen, it’s really going to force growth from a policy perspective,” Mr. Schwarzman said at the conference.

Despite his support for Mr. Trump’s policies, Mr. Schwarzman has signaled privately that he would not commit to a full-time position in the administration, but was otherwise interested in helping to advise the president-elect.