US President Joe Biden has stood down his campaign for re-election and endorsed Vice-President Kamala Harris to succeed him as the Democratic presidential candidate.

In a statement posted on X, he confirmed he will fulfil duties for the rest of his term.

The President was facing pressure to step down amid concerns about his age and mental fitness.

He wrote: “It has been the greatest honour of my life to serve as your President. And while it has been my intention to seek re-election, I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as President for the remainder of my term.

“I will speak to the nation later this week in more detail about my decision.

“For now, let me express my deepest gratitude for all those who have worked so hard to see me re-elected.

“I want to thank Vice-President Kamala Harris for being an extraordinary partner in all this work. And let me express my heartfelt appreciation to the American people for the faith and trust you have placed in me.”

He added on the social media platform: “My fellow Democrats, I have decided not to accept the nomination and to focus all my energies on my duties as President for the remainder of my term.

“My very first decision as the party nominee in 2020 was to pick Kamala Harris as my Vice-President. And it’s been the best decision I’ve made.

“Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year.

“Democrats, it’s time to come together and beat Trump. Let’s do this.”

The Vice-President posted on X: “On behalf of the American people, I thank Joe Biden for his extraordinary leadership as President of the United States and for his decades of service to our country.

“I am honoured to have the President’s endorsement and my intention is to earn and win this nomination.”

Former US president Donald Trump was last week officially nominated as the Republican Party candidate for the November 5 election.