The party continued Tuesday night in Washington, D.C. as Lady Gaga – and a surprise guest in Tony Bennett – performed at the final inaugural ball to celebrate President Obama’s second swearing-in ceremony.

Lady Gaga – real name Stefani Germanotta – re-tweeted some photos from the event, which was held for campaign staffers at the Washington Convention Center. Following remarks from President Obama and Joe Biden, Gaga – wearing a white outfit reminiscent of Glinda the Good Witch – took to the stage and sang some of her biggest hits, including Born This Way and Edge of Glory.

PHOTOS: Lady Gaga Hides Her Assets With Coconut

At the end of her set, the legendary Tony Bennett, 86, surprised the crowd by joining Gaga, 26, on stage for a duet on The Lady is a Tramp. (They first recorded the Rodgers & Hart classic together in 2011 for Bennett’s Duets II album.) Gaga wrapped up her performance by explaining she had to leave to make it to a concert in Phoenix Wednesday night.

RELATED STORIES:

PHOTOS: Lady Gaga Takes Stage In Milan

Joan Rivers Defends Kelly Osbourne Against Lady Gaga

Sharon Osbourne Rips Lady Gaga: You’re A Bully & A Hypocrite!

ON YOUR RADAR 2012: The Worst And Wackiest Dressed Stars Of The Year