Democrat Joe Biden, 81, is America’s oldest president. His chief rival, Republican Donald Trump, is 77. Polls consistently show voters are more worried that Mr Biden lacks “mental sharpness.” Today, why President Biden’s age matters, with our Medical Editor, Fergus Walsh, and our Special Correspondent in Washington, Katty Kay.

The Global Story brings you trusted insights from BBC experts around the world, with Katya Adler.

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Today’s episode of The Global Story was made by Neal Razzell and Emilia Jansson. The technical producers were Matt Dean and Tom Brignell. The assistant editor is Sergi Forcada Freixas and the senior news editor is Jonathan Aspinwall.