Former and future President Donald Trump is set to visit his old office today, the Oval Office. President Biden invited his predecessor and successor for what is a ceremonial tradition meant to signal the desire for a smooth and peaceful transfer of power.

In 2020, Trump refused to accept the results of the election and did not invite Biden to the Oval Office.

But in 2016, then-President Barack Obama sat next to Trump in the Oval Office just two days after Trump beat Democratic candidate Hillary Clinton.

Sitting side by side, Trump called Obama a "very good man," said it was an honor to meet with him and that he looked forward to being with him "many, many more times in the future."

It didn't take long for Trump to sour on Obama. But there in the Oval Office, with cameras aimed at them, the two presidents had an almost friendly rapport.

Obama said he wanted to facilitate a transition that would set Trump up for success. "I believe that it is important for all of us, regardless of party and regardless of political preferences, to now come together, work together, to deal with the many challenges that we face," Obama said.

Meanwhile Trump raved about how long the meeting lasted.

"This was a meeting that was going to last for maybe 10 or 15 minutes, and we were just going to get to know each other," Trump said. "We had never met each other. I have great respect. The meeting lasted for almost an hour and a half. And it could have -- as far as I'm concerned, it could have gone on for a lot longer."

The one piece of advice Obama gave Trump while reporters were in the room was, "Don't answer the questions when they just start yelling it."

That's something Trump immediately ignored when in office. He frequently held court as reporters shouted questions, responding to the ones he felt like answering and sometimes sparring with the journalists.

The tradition is part of the transfer of power

If the Trump-Obama relationship was strained, the one between Biden and Trump is even worse. Biden campaigned against Trump twice, winning in 2020 with an argument that Trump was an existential threat to U.S. democracy.

Then during the 2024 campaign, their one meeting on a debate stage in late June essentially ended Biden's bid for a second term. During the remaining months of the campaign Trump often gloated about his knock-out punch in the debate and bemoaned the "coup" that forced Biden out of the race.

But, the day after the election, Biden phoned Trump to congratulate him and invited him to the White House for a meeting.