State of the Union: Obama regrets era of 'rancor' and ponders divided America

President says it's biggest regret of presidency but appeals to America's better self in calling for rejection of hostile rhetoric: 'We can't afford to go down that path'

Barack Obama admitted his regret that he will leave the US more, not less, polarised when he departs office a year from now, using his final State of the Union address to urge the nation not to succumb to demagogues.

The man who declared "We are not a collection of red states and blue states. We are the United States of America" while campaigning in Iowa in 2008 conceded that, as his presidency comes to close, the American political divide runs deeper than ever.