Democratic US presidential candidate Joe Biden has chosen his running mate for the Nov. 3 election and could announce his pick as soon as Tuesday, according to a source familiar with the matter.Finalists for the job have been informed of Biden's decision, the source said, speaking on condition of anonymity. A Biden campaign spokesman did not immediately respond to a request for comment.The news that Biden has made his selection was first reported by CNN. The network also reported that US Representative Karen Bass of California, who was under serious consideration, has told people she was not chosen.Biden, who served as vice president under President Barack Obama, has pledged to elevate a woman as his running mate. At least a dozen candidates have received various levels of interest from the campaign, according to interviews with Democratic officials and Biden allies.His short list has included several Black lawmakers and leaders, including Senator Kamala Harris of California, one of his Democratic primary rivals for the presidential nomination, and former national security adviser Susan Rice.No major-party presidential ticket has ever included a Black woman. But Biden has faced increasing pressure to tap a woman of color following months of protests over racial inequity after the police killing of George Floyd, a Black man, in Minneapolis.Biden, 77, is leading Republican President Donald Trump, 74, in national opinion polls.Biden's deliberations have drawn intense scrutiny given his age as well as speculation that he might serve only one four-year term if elected. He would be the oldest US president in history.