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, and added gasoline to a smoldering Democratic party movement questioning the wisdom of his second term. Within days, Biden went from the party's figurehead to a liability.