These were some of the key moments that led to Biden’s decision to step down. U.S. President Joe Biden’s decision to end his reelection campaign on Sunday followed a series of strategic missteps by his campaign team and White House aides that amplified concerns that the 81-year-old president wouldn’t be able to win in November’s election or run the country for another four years.Biden’s halting performance at the June 27 presidential debate against Republican candidate Donald Trump, pushed even some of his closest allies to question whether he could endure a full campaign That episode in fact …