Mitt Romney has left the White House, after a lunch with President Barack Obama that apparently lasted just over an hour.

Mitt Romney arrivers for lunch at the White House with President Obama (YouTube)

He was seen walking into the West Wing alone after arriving in a black SUV, and was seen leaving a little over an hour later.

For Romney, this was a day of closure after a hard-fought campaign. Earlier today, Romney met with his former running mate, Wisconsin congressman Paul Ryan -- and, according to an aide to Ryan, they discussed the "fiscal cliff" negotiations and other economic challenges facing Washington.

In a statement after the meeting, Ryan said he's "grateful" to Romney for "the honor of joining his ticket" -- and that he's "proud of the principles and ideas" that they advanced during the campaign.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)