WASHINGTON // Barack Obama and the senator Joe Biden made their first official appearance together yesterday in front of supporters at the Old State Capitol in Springfield, Illinois, the same spot where Mr Obama kicked off his campaign more than a year ago. Mr Obama's choice of Mr Biden as running mate is seen as a bid to add experience and foreign policy expertise to his White House campaign. The presumptive Democratic presidential nominee has been lauded for his idealism and energy, but detractors have criticised his lack of international and foreign policy credentials at a time when the United States is engaged in costly wars in Iraq and Afghanistan. Mr Biden, the son of an Irish-Catholic car salesman from the industrial city of Scranton, Pennsylvania, was elected to the senate in 1972 - several years before John McCain, Mr Obama's Republican rival, entered politics - and has sat on its foreign relations committee for more than three decades. Moreover, his son will be deployed to Iraq in October, which the Democrats hope will go some way towards countering the extensive military record of Mr McCain, who spent five years in captivity in Vietnam and who is generally viewed as stronger on foreign policy issues.