When Barack Obama was crowned as the Democratic presidential nominee in Denver in 2008, he praised Hillary Clinton as a “champion for working Americans” in an effort to enlist his vanquished rival’s supporters for his election battle with John McCain.
The US president will face a similar challenge when he addresses the Democratic convention on today. But now he must convince fans of Bernie Sanders, who lost the primary to Mrs Clinton, to rally behind his former secretary of state as she prepares for the fight of her life against Donald Trump.
Speaking two nights after his wife Michelle gave a powerful speech urging Democrats to “knock on every door” for Mrs Clinton, Mr Obama will act as one of several high-profile surrogates in her race for the White House.