US President Joe Biden will address the nation on Wednesday to explain to fellow Americans his decision to withdraw from the presidential race and endorse his deputy Kamala Harris to be the nominee of the Democratic Party for the November general elections.

Biden, 81, returned to the White House on Tuesday afternoon after spending nearly a week at his Delaware residence, where he had self-isolated after he tested positive for COVID-19 while campaigning in Las Vegas.

“Tomorrow evening at 8 PM ET (early Thursday morning local India time), I will address the nation from the Oval Office on what lies ahead, and how I will finish the job for the American people,” Biden said on Tuesday.

During his quarantine period, Biden sent political shockwaves around the country on Sunday with a post on social media announcing that he was not accepting the Democratic presidential nomination. He endorsed Vice President Kamala Harris, 59, as the Democratic Party's new nominee.

The announcement came after mounting pressure about Biden's age and ability to challenge Republican rival and former president Donald Trump.

“This afternoon, I arrived back at the Oval Office and sat down with my national security team for my daily intelligence briefing. Serving as your Commander-in-Chief continues to be the greatest honour of my life,” he said in a post on X.

Biden also posted a picture of him entering the White House residence on his arrival.

“It's great to be back at the White House,” he said.

This would be the second time this month that Biden would address the nation. He addressed the country on July 14, a day after the failed assassination bid on the former president and Republican presidential nominee Trump.