Comedian Wanda Sykes roasted U.S. President Barack Obama and the press gallery at the annual White House correspondents' dinner on Saturday. (Peter Kramer/Associated Press)

Not even the president of the United States was off limits when tart-tongued comedian Wanda Sykes took the floor at the annual White House Correspondents' Association dinner on Saturday.

She said President Barack Obama has been so busy trying to be all things to all Americans that the next thing is that he'll be seen mowing the White House lawn.

"It's amazing, the first black president – I know you're biracial – but the first black president!" she said. "That's unless you screw up. Then it's going to be, 'What's up with the half-white guy, huh?'"

Sykes, 45, best known for her role as Barb on The New Adventures of Old Christine and for playing herself on Curb Your Enthusiasm, was the first African-American woman and the first openly gay person to entertain at the annual black-tie gala.

Of course, whether her standup gig was funny depended on audience members' political views.

She speculated that Rush Limbaugh, host of the nationally syndicated radio talk show, The Rush Limbaugh Show, was actually the 20th hijacker on Sept. 11, 2001.

She derided Sean Hannity, host of The Sean Hannity Show, for not living up to his pledge to be waterboarded for the troops.

She made a funny, albeit off-colour, joke about former vice-presidential candidate Sarah Palin bowing out of the dinner: "She pulled out at the last minute. Someone should tell her that's not really how you practise abstinence."

She gave the president's wife, Michelle Obama, a back-handed compliment: "How dare you give [her] grief about showing her arms. The country's broke! Sleeves cost money! … She has beautiful arms. Some of the previous first ladies, they needed sleeves. Some of them needed ponchos."

And she took on critics of the president's choice of dog: "Why didn't he get a rescue dog? … Look, the man has to rescue a country that was abused by its previous owner. Let him have a fresh start with a dog."

Sykes has said it's her job to "poke fun and ridicule."

The $200 US-a-ticket dinner attracted journalists and VIPs from outside the political realm. These included actors Christian Slater and Natalie Portman and British rock musician Sting.

The White House Correspondents Association was formed in 1914 as a liaison between the American press and the U.S. president.

With files from The Associated Press