WASHINGTON President Barack Obama mixed comedy with some early campaigning Saturday night at the White House Correspondents' Association annual dinner, focusing mainly on Donald Trump.

With Trump in attendance, Obama said the billionaire businessman has shown the acumen of a future president, from firing Gary Busey on a recent episode of "Celebrity Apprentice" to focusing so much time on conspiracy theories about Obama's birthplace.

After a week when Obama released his long-form Hawaii birth certificate, he said Trump could now focus on the serious issues: "Did we fake the moon landing? What really happened in Roswell? And where are Biggie and Tupac?"

Trump chuckled.

The billionaire businessman was among those who arrived for the annual dinner, after a week when he challenged the president on conspiracy theories about his birthplace and the White House released Obama's birth certificate.

Newt Gingrich, another considering a presidential run in 2012, also was among the guests. Virginia Gov. Bob McDonnell and Obama confidant and Chicago Mayor-elect Rahm Emanuel were among those milling in the foyer with figures from the entertainment world such as actors Sean Penn and Scarlett Johansson.

About 3,000 people were expected to attend.

Obama arrived a day after traveling to Alabama to meet with residents affected by the deadliest tornado outbreak in 40 years.

But in Washington, a town consumed by politics and partisanship, the dinner is typically a light-hearted affair and an opportunity for the president to show off his humorous side. Obama has used his past appearances to crack jokes at everything from the infamous couple that crashed his first state dinner to the off-the-cuff speaking style of his vice president, Joe Biden.

"Saturday Night Live" comedian Seth Myers provided more jokes after the president.

Some proceeds from the dinner pay for journalism scholarships.

Several journalists were to be honored at the dinner: Dan Balz of The Washington Post and Jake Tapper of ABC News, Peter Baker of The New York Times and Michael Berens of The Seattle Times.