Joe Biden has withdrawn from his presidential re-election race and endorsed Vice-President Kamala Harris to take his place at the top of their party’s ticket, an extraordinary decision upending American politics that plunges the Democratic nomination into uncertainty just months before the November election against Donald Trump – a candidate Biden has warned is an existential threat to US democracy.“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 focus solely on fulfilling my duties as president for the remainder of my term,” Biden said in a letter announcing his decision.Biden made the stunning announcement after a weeks-long pressure campaign by Democratic leaders, organisers and donors who increasingly saw no path to victory so long as the embattled incumbent remained on the ticket. More than 30 Democratic members of Congress had called on Biden to step aside.In a post on Truth Social, Trump said Biden “was not fit to run for President, and is certainly not fit to serve – And never was!”Biden “only attained the position of President by lies, Fake News, and not leaving his Basement”, Trump said. “All those around him, including his Doctor and the Media, knew that he wasn’t capable of being President, and he wasn’t.”Trump went on to list a series of falsehoods about immigration, concluding: “We will suffer greatly because of his presidency, but we will remedy the damage he has done very quickly. MAKE AMERICA GREAT AGAIN!”