'I can't think of anything': Obama told Trump that he couldn't recall his biggest mistake, book says

• Trump reportedly asked Obama to reveal his biggest mistake, according to a new book.
• In January 2017, Trump and Obama rode in a car together on the way to the presidential inauguration.
• Obama reportedly paused and looked at Trump before saying that he couldn't recall such a mistake.

For years, former Presidents Barack Obama and Donald Trump have been political adversaries, which was never more evident than during the 2016 presidential election.

Obama felt that former Secretary of State Hillary Clinton, the Democratic presidential nominee that year, was supremely qualified to be commander-in-chief thanks to a career in public service as a US Senator from New York as well as her work as the top US diplomat.

However, after Clinton lost the presidential election to Trump, Obama had to start planning for what was next.

On January 20, 2017, as Trump was set to be inaugurated as the 45th US president, Obama rode in a presidential limousine with him and Republican Sen. Roy Blunt of Missouri from the White House to the Capitol.

During the ride, Trump asked Obama if he could name his biggest mistake, according to a new book by Washington Post journalists Bob Woodward and Robert Costa.

The book, "Peril" - an early copy of which was obtained by Insider - details an interaction between the two men that could have ended up as a lengthy conversation but simply fell flat.

While in the car, Trump turned to Obama and asked a question: "What was your biggest mistake?" the president-elect reportedly asked his Democratic counterpart.

Woodward and Costa reported that Obama paused and looked at Trump. "I can't think of anything," the outgoing president said.

Trump then sought to change the subject, inquiring about the vehicle. "Is this the car you use all the time?" he asked Obama.

In "Peril," Woodward and Costa describe how Trump came full circle from that moment with Obama.

As Joe Biden was set to assume the presidency on Inauguration Day in January 2021, Trump chose not to attend the ceremony and instead left the White House early with then-first lady Melania Trump, taking a helicopter to Joint Base Andrews in Maryland before flying to Florida on his final trip on Air Force One.