Washington - True to his word, former President Jimmy Carter is en route to Washington for Donald Trump's inauguration.

A tipster sent this picture from his Delta Air Lines flight from Atlanta, along with a note that he walked up and down the aisles to shake hands with the passengers.

For a time, the Georgia Democrat had been the only ex-president to formally RSVP to the Friday swearing-in ceremony.

That changed a few weeks ago when President Bill Clinton sent word to reporters that he'll attend the inaugural along with Hillary. So did George W. Bush, although his father, George H.W. Bush, won't attend because of his ailing health. (He wrote a note to Trump saying his doctors warned him sitting in the cold would put him "six feet under.") And President Barack Obama will also be there to formally hand over the keys to the White House.

It was not a given that any of those ex-White House denizens would attend the bash. Trump repeatedly mocked Jeb Bush during the GOP primary, casting him as a low-energy tool of the establishment. Bush '41 and Bush '43 both refused to endorse Trump in the general election, and Barbara Bush and Jeb Bush openly opposed him.

And Trump ran a bitter campaign against Hillary Clinton, invoking scandals from Bill Clinton’s past in the final stretch of the race – and vowing to sic a special prosecutor on the former secretary of state to probe her use of a private email server.

Carter, 92, told his Sunday school class shortly after the election that he'd attend Donald Trump's inauguration. But he showed little affinity for either candidate.

He supported Clinton – "everybody knows that I'm a Democrat and I'll be voting Democratic," he said – but he did little to actively campaign for her. And he noted she was "quite unpopular" in one August interview.

As for Carter's stance on Trump, the Georgia Democrat said during a speech before the British House of Lords last year – before Trump locked up the nomination – that the New York businessman might not be the worst Republican in the field.

“The reason is, Trump has proven already he’s completely malleable,” Carter said then. “I don’t think he has any fixed (positions) he’d go the White House and fight for. On the other hand, Ted Cruz is not malleable. He has far right wing policies he’d pursue if he became president.”