Four living presidents -- and one dead one -- announce the end of the David Letterman 'nightmare'
President Barack Obama appears during David Letterman's opening segment on May 20, 2015. [Mashable]

David Letterman opened his final Late Show on Wednesday with a light nod to politics, with former President Gerald Ford informing the viewers, "Our long national nightmare is over."

Ford was followed by four of the country's five living presidents -- George H.W. Bush, Bill Clinton, George W. Bush and Barack Obama -- repeating the line, with Obama adding the punchline.

"Our long national nightmare is over -- Letterman is retiring," Obama says, drawing Letterman on-camera.

"You're just kidding, right?" Letterman asks Obama, only to get a shrug.

Mashable posted a gif of Obama's interaction with Letterman:

The opening sequence, as posted online on Wednesday, can be seen below.