Sir Paul brought down the house by belting out "Michelle," to Mrs Obama.

An all-star lineup of performers had gathered to sing some of Sir Paul's greatest hits.

Stevie Wonder had the Obamas clapping to "We Can Work It Out." The Jonas Brothers did "Baby You Can Drive My Car." Corinne Bailey Rae sang "Blackbird" and Faith Hill performed "Long and Winding Road."

But Sir Paul brought down the house by belting out "Michelle," to Mrs Obama.

He said he'd been "itching" to perform it at the White House, and asked the president's forgiveness in advance. The first lady was soon mouthing the words along with Sir Paul as the president swayed in his seat.

After serenading the first lady with the lyrics "I love you, I love you, I love you," Sir Paul noted that he might be the "first guy ever to be punched out by a president."

The night culminated in Mr Obama's presentation to Sir Paul of the Gershwin Prize for Popular Song, awarded by the Library of Congress.

The former Beatle said it was a moment like no other.

"I don't think there could be anything more special than to play here," he said, offering to make it a regular gig.

"Lunchtimes, we could come around," he offered. "We're cheap."

Sir Paul, 67, left no question about how he felt about Mr Obama, telling the president that in tough times, "You have billions of us who are rooting for you and we know you are going to come through."

Later, after the TV cameras had left, he expressed appreciation for the Library of Congress and added a zinger: "After the last eight years, it's great to have a president who knows what a library is."