Bumbling Joe Biden said Donald Trump is the 'sitting President' as the confused 81-year-old stumbled through an economic speech in South Carolina over the weekend.

The President tried to shore up support for another term as he tore into the former president during a dinner on Saturday that celebrated the state and its large base of black voters.

Along with bashing Trump about his view on the US economy, Biden also said his Republican rival failure to support the rights of black citizens was a threat to democracy.

'The American consumers are facing real confidence in the economy we're building. Let me tell you who else is noticing that- Donald Trump,' Biden said in his speech.

The President then started to fumble his words as he tried to collect his thoughts and said: 'Did you see what he recently said about- he wants to, he wants to see the economy crash this year? The Sitting President.'