text:  Questions about Mr Biden's health and mental acuity were given added urgency when he performed poorly in the first presidential debate with Donald Trump at the end of June. Since then, there have been calls for him to step aside. Some prominent donors and some within the party often briefing anonymously. Well, one Democratic congressman who has broken cover to openly call for a new candidate is Adam Smith. He's been telling my colleague James Cocknell why Mr Biden should be a one term president.