US President Joe Biden announced on Sunday that he was dropping out of his re-election battle with Donald Trump, in a historic move that plunges the already turbulent 2024 White House race into uncharted territory. “It has been the greatest honor of my life to serve you as president,” the 81-year-old Democrat said in a letter published on social media platform X, posted while he was recovering from Covid at his beach house in Delaware. “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 f…