WASHINGTON ― The current and former living U.S. presidents said goodbye to Jimmy Carter on Thursday, and in the process once again highlighted the contrast between former and soon-to-be President Donald Trump and all the others.

Trump is obviously no fan of Biden, but Obama and his veep also have a famously complex relationship, only made more so after Obama helped nudge Biden to quit the presidential race last summer. Surely Obama feels some frustration that Biden fumbled a possibly winnable race; maybe he couldn’t help spill to his sworn enemy?

One of the first calls Obama made after U.S. forces killed Osama bin Laden in 2011 was to George W. Bush to spread the word that the mission had been accomplished, said Kate Andersen Brower, author of “Team of Five: The Presidents Club in the Age of Trump.”