With neither president revealing what the pair spoke about, speculation has mounted about the details of their conversation.

Other former presidents and first ladies are expected to attend as are tech billionaires Elon Musk, Mark Zuckerberg and Jeff Bezos.

Incoming First Lady Melania Trump has accused Barack and Michelle Obama of withholding information from her husband when he first moved into the White House.

The former president and once-again-future president, who are historically something less than besties, chatted it up before the service began. (Michelle Obama was not in attendance.)

Former first lady Michelle Obama will not attend President-elect Donald Trump's inauguration on Monday, her office confirmed to ABC News.

The planned absence Monday follows another notable absence last week at the state funeral of former president Jimmy Carter.

Former Presidents Barack Obama, Bill Clinton and George W. Bush will come together again next week for the inauguration of President-elect Donald Trump, but one spouse, Michelle Obama, is sitting this one out.

According to a new report, former first lady Michelle Obama will be skipping Donald Trump's inauguration because she can't hide her personal feelings about him.