Alone on his 49th birthday, US president Barack Obama fled the empty White House mansion and headed for a more intimate celebration with long-time friends in his Chicago home town.

Mr Obama has been living a bachelor's life for the past several days with first lady Michelle and daughter Sasha visiting Spain and daughter Malia spending the month away at an undisclosed summer camp.

But before leaving Washington with the family dog Bo, Mr Obama got a couple of presents he did not have to unwrap and which the White House described as being the highlight of his day: telephone calls from the women in his life.

Mrs Obama and Sasha phoned in with their birthday wishes, followed by a lunchtime call from Malia.

"Needless to say ... both those calls were the highlights of his day," White House press secretary Robert Gibbs told reporters who travelled with Mr Obama aboard Air Force One.

Mr Obama's Secret Service detail got him a present, though Mr Gibbs would describe it only as "heartfelt".

As the presidential motorcade pulled closer to his house in Hyde Park, neighbours lined the street to welcome him home with waves and signs, including "Happy 49th Birthday President Barack Obama" and "Happy Birthday Mr President".

Mr Obama continued his birthday celebration over a leisurely, two-hour dinner with friends at graham elliot in Chicago's River North neighbourhood. His dinner companions included long-time friends Eric Whitaker, Marty Nesbitt and Valerie Jarrett, also a senior White House adviser and fellow Chicagoan.

Mr Obama's birthday - though a year short of the milestone 50 - also was viewed in this election year as a prime fund-raising opportunity for Democrats, who fear losing their hold on both houses of Congress come the November elections. Emails, house parties and other forms of outreach sought to capitalise on Mr Obama's big day.

Mrs Obama even joined the act, asking supporters to sign an email birthday card being distributed by Organising for America, Mr Obama's political organisation. More than 1.2 million people had signed it yesterday.

The Republican Party marked the occasion too, with a new website offering 11 different e-cards people can send Mr Obama, including ones mocking the ethics problems of Democratic Reps Charles Rangel and Maxine Waters, and noting key Democratic election losses in Virginia, New Jersey and Massachusetts.

Mr Obama planned to help out with the money-raising today by headlining separate events in Chicago for the Democratic Party and Alexi Giannoulias, the Democrat eyeing the Senate seat Obama gave up to become president.

The president spoke yesterday at an AFL-CIO meeting in Washington and joked about not getting a birthday cake from his "good friends" in the union movement.

A cake apparently had been planned, according to union president Richard Trumka, but he said the Secret Service had cancelled the idea.

Mr Obama said he would have a talk with the agents then joked: "They're probably eating it right now."

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