 Hello there. You're listening to The Newsroom from the BBC World Service with me, Nick Miles. Simmering concerns over President Biden's fitness to run against Donald Trump have been bubbling to the surface. This comes, of course, after Mr Biden's disappointing TV debate performance. One Democrat congressman, Lloyd Doggett, now has urged him to step aside. And former Democrat Speaker Nancy Pelosi said it's reasonable to question the mental aptitude of each candidate.