Michael D'Antonio, a CNN contributor and biographer who wrote "The Truth About Trump," told CNN on Sunday that he believes President TrumpDonald John TrumpCoast Guard chief: 'Unacceptable' that service members must rely on food pantries, donations amid shutdown Dem lawmaker apologizes after saying it's never been legal in US to force people to work for free Grassley to hold drug pricing hearing MORE was "stewing" as political leaders past and present united to honor the late Sen. John McCainJohn Sidney McCainOvernight Health Care: HHS chief refuses to testify on family separations | Grassley to test GOP on lowering drug prices | PhRMA spends record on lobbying in 2018 Will a Democratic woman break the glass ceiling in 2020? Republican state lawmaker introduces bill that would tax porn to fund Trump's border wall 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 TrumpDocuments indicate detailed plans for Trump Tower Moscow: report The Hill's Morning Report — Trump’s new immigration plan faces uphill battle in Senate China grants Ivanka Trump's defunct company five trademarks MORE and Jared KushnerJared Corey KushnerDem senator: 'Putin had something on' Trump which may account for 'plainly false' statements Christie says Trump hired 'riffraff' in new book Trump pitches new plan to reopen government amid Dem pushback 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 PencePence urges Venezuelans to back opposition leader ahead of anti-government protests Mueller coverage keeps missing its mark, as BuzzFeed debacle shows Obama puts out call for service on MLK Day: ‘Make a positive impact on the world’ 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.