The chief of staff position is one of the most important at the White House, the senior political appointee responsible for driving the president's policy agenda and ensuring appropriate staff members are hired.

This is the latest in a series of revelations about the apparently improper storage of papers dating from Biden's time as Barack Obama's vice-president.

This comes after a furor over secret papers found at his former office exploded with the discovery of a second batch.

The Congressional Budget Office in September calculated that the debt forgiveness programme run would cost taxpayers about US$400 billion.

Various recent polls say a majority of Americans do not want Biden to run again.

Biden, who turns 80 on Nov 20, referred to Prime Minister Hun Sen of Cambodia as the prime minister of Colombia.

Final results may not be known until days – or in some cases even weeks – after election day, setting the stage for what promise to be acrimonious challenges.

Up for grabs are all 435 House seats, a third of the 100 Senate seats, and a slew of state-level posts.

The messages were formatted to look like normal tweets usually posted by The New York Post, which is owned by NewsCorp, the media empire owned by Australian billionaire Rupert Murdoch.

More releases may be possible if energy prices spike, the senior US official says.

Biden had said that Pakistan is 'maybe one of the most dangerous nations in the world' as it has 'nuclear weapons without any cohesion'.

The US president also downplays the likelihood of a recession but concedes a 'slight' downturn is possible.