Michael D'Antonio, a CNN contributor and biographer who wrote "The Truth About Trump," told CNN on Sunday that he believes President TrumpDonald John TrumpForget the spin: Five unrefuted Mueller Report revelations Lara Trump: Merkel admitting migrants 'one of the worst things that ever happened to Germany' Financial satisfaction hits record high: survey MORE was "stewing" as political leaders past and present united to honor the late Sen. John McCainJohn Sidney McCainBiden's sloppy launch may cost him Cindy McCain weighs in on Biden report: 'No intention' of getting involved in race Why did Mueller allow his investigation to continue for two years? MORE (R-Ariz.) this weekend.

“This is a man who is really impatient when anyone else has the public’s attention,” D’Antonio told CNN's Ana Cabrera.

“He is so devoted to drawing attention to himself that he has to be restrained from tweeting when it would be against his own interests," he added. "I think that even the act of going golfing during the ceremony yesterday demonstrated who he really is.”

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Trump did not attend services for McCain throughout the weekend, instead visiting his golf club in Virginia on Saturday and Sunday.

Vice President Pence spoke at a memorial service at the U.S. Capitol on Friday, while White House advisers Ivanka TrumpIvana (Ivanka) Marie TrumpAuthor of book on Kushners mocks Jared: He couldn't get a TSA PreCheck without Trump's help Africa's women can change a continent: Will Ivanka give them her full support? A Trump visit to Africa is important — and carries some urgency MORE and Jared KushnerJared Corey KushnerDemocrats are playing voters on their fantasies for impeachment Author of book on Kushners mocks Jared: He couldn't get a TSA PreCheck without Trump's help What Jared Kushner has to tell Donald Trump on immigration MORE attended Saturday's memorial at the Washington National Cathedral.

“I think it pointed up the president’s absence but in many instances, Ivanka is the person that represents humanity in place of the president,” D'Antonio said. “I think it was to his benefit she [did] so. Just as it was to his benefit that Mike PenceMichael (Mike) Richard PenceDemocrats' CNN town halls exposed an extreme agenda Weld: 'We would be much better off with a President Mike Pence' Gabbard: Trump, Pence 'try to hide the truth' of Saudi-inspired terrorist attacks from Christian supporters MORE delivered an address on Friday.”

While Trump was not present at Saturday's memorial, multiple speakers took subtle jabs at the president, with Meghan McCain stating in her eulogy that her father's America "is already great."

John McCain, who died last week at age 81 after being diagnosed with brain cancer, was buried on Sunday at the U.S. Naval Academy in Annapolis, Md.

Trump and McCain had a fraught relationship, with the Senate icon remaining one of the president's staunchest Republican critics even after his cancer diagnosis.

Trump drew criticism when he waited nearly 48 hours after McCain's death to issue a statement expressing "respect" for the late senator.