The invited donors and their families have combined to donate millions of dollars to committees supporting Mr. Trump’s campaign and inauguration, and Mr. Trump’s team hopes they will contribute millions more to groups pushing his legislative agenda. They included the New York investor Robert Mercer, the Kentucky coal executive Joseph W. Craft and the Wisconsin roofing magnate Diane Hendricks, according to people familiar with the dinner.

Mr. Mercer’s presence was noteworthy, since the White House confirmed Friday that Mr. Trump’s chief strategist, Stephen K. Bannon, had been ousted. Mr. Mercer has long funded the political and business activities of Mr. Bannon, who was brought onto Mr. Trump’s campaign at the recommendation of Mr. Mercer’s daughter, Rebekah Mercer.

A source familiar with the dinner said that Mr. Bannon’s future was not a topic of conversation.

But the day before the dinner, Mr. Bannon and Mr. Mercer huddled for hours at Mr. Mercer’s Long Island estate to discuss possible ventures.

In a statement, Rebekah Mercer said she and her father were “ecstatic to have him back at the helm of Breitbart News, where he will continue to fight for personal liberties and against an elite establishment that seeks, above all else, to amass its own power at the expense of the people.” Two people close to the Mercers said they never favored Mr. Bannon being in the White House, and they noted that their support for Mr. Trump came late in the campaign.

Other donors also were invited to Thursday’s dinner but did not attend, including Paul Singer, the New York hedge fund billionaire.