Senator Barack Obama picks Senator Joseph R. Biden Jr. of Delaware to be his running-mate

Mr. Biden has run twice for the presidency himself, once in 1988 and again in 2008, dropping out early in both cases. Mr. Biden quit the presidential race this year he came in fifth place in Iowa. He was forced to quit the 1988 presidential race in the face of accusations that he had plagiarized part of a speech from a Neil Kinnock, the British Labor Party leader. Shortly afterward, he was found to have suffered two aneurysms, NY TIMES reports.

News of Mr. Obama’s decision leaked out hours before his campaign was scheduled to inform supporters via text and e-mail messages. Obama's campaign have arranged a debut for Joe Biden on Saturday outside the Old State Capitol in Springfield, Ill.

The Democratic National Convention meets next week in Denver to hand Obama his presidential nomination, and then confirm Biden.

In selecting Biden, Obama passed over lady Hillary Rodham Clinton, his rival across months of primaries and caucuses. There is talk that Clinton was never considered as several aides to Clinton said the Obama campaign had never requested financial or other records from her.

Biden was elected to the Senate at the age of 29 in 1973. Biden will make his first big speech as the VP candidate on Wednesday, August 27 -- the third night of the Democratic convention.