Obama: I was actually black before I got elected

US president Barack Obama has dismissed claims that racism is behind the fierce opposition to his plans for reform in a joke during an appearance on David Letterman's late night chat show.

Appearing as a guest on the show for the first time since taking office, Mr Obama quipped: 'I was actually black before the election.'

Former US Jimmy Carter president sparked controversy recently when he claimed conservative opposition to Mr Obama's healthcare reforms were rooted in racism.

Mr Obama moved to quash the accusations though, saying the fact he was the first African-American to be elected into the White House was an indication of the state of race relations in the US.

'First of all, I think it's important to realise that I was actually black before the election,' he joked.

'One of the things that you sign up for in politics is that folks yell at you. Whenever a president tries to bring about significant changes, particularly during times of economic unease, there is a certain segment of the population that gets very riled up.'

The US president told Letterman on Monday he appreciated the general public's weariness at the ongoing war in Afghanistan and the calls for US troops to be brought home.

Leading commanders in the US military, however, have warned more troops need to be deployed if the war is to be one, and Mr Obama admitted careful thought and a clear strategy was needed.

'The country is weary of the war. What I'm trying to do at this point is to make sure that... we have got a coherent strategy that can work,' he said.

'I'm going to be asking some very hard questions.'

The appearance on The Late Show with David Letterman is just the latest in a series of media appearances by the president in the last few days as he continues to try and inform the US public of his long-term plans.