Barack Obama has sung in public for the second time this year, at the urging of Mick Jagger. The Rolling Stones frontman was taking part in a White House blues show with blues legends BB King and Buddy Guy and invited the US President to sing along to "Sweet Home Chicago." To cheers from the audience, a smiling Obama sang parts of the tune, an ode to his adopted hometown, originally made famous by the legendary bluesman Robert Johnson. Obama singing soul legend Al Greens "Lets Stay Together" was a hit last month – one of the videos of him crooning "Im so in love with you," at New Yorks famed Apollo Theater in Harlem, has been viewed over five million times on YouTube.