A majority of Americans believe neither President Biden nor former President Donald Trump are “fit to serve another term” in the Oval Office — and almost half might back a third-party candidate next year if the two are their party’s nominees, according to two recent polls. A Yahoo News/YouGov survey found 55% of US adults believe Biden is unfit for the presidency, and 53% say the same of Trump. When asked their reasoning, 20% of Americans say Biden, 80, is “incompetent,” 12% say he is “too old,” 10% say he is “corrupt,” 9% say he is “doing a bad job,”...