First lady Michelle Obama has taken their youngest daughter, Sasha, to Spain. Their other daughter, Malia, is away at summer camp.
Obama hasn't shied away from talking about his birthday, noting that his hair is getting grayer and his metabolism is slowing down as another year passes. White House press secretary Robert Gibbs says that while there's no doubt that the presidency comes with enormous physical and mental strain, Obama "greatly enjoys" the job.
Obama is heading home to Chicago for a birthday celebration dinner Wednesday evening with friends. He'll spend the night in his own house in the city's Hyde Park neighborhood.
Earlier in the day, during remarks at a meeting of the AFL-CIO's governing executive council, Obama joked that he was disappointed that there wasn't a cake.
"I'm going to have to talk to Secret Service," Obama said. Then, casting a glance toward the agents, he said teasingly, "They're probably eating it right now."
But there was a present even better than cake awaiting Obama on his birthday - news Wednesday that efforts to plug the blown-out well in the Gulf of Mexico are succeeding, prompting officials to suggest that no more oil is likely to leak into the water.
Meanwhile, the president's birthday - though a year shy of the Big 50 milestone - is being used in this election year as a prime fundraising opportunity for Democratic candidates and party organizations, through mailings, e-mails, parties and other birthday-themed outreach.
On Thursday, Obama will tour an auto plant in Chicago and attend Democratic fundraisers before returning to Washington.