Last week it was announced that Donald Trump and Joe Biden would finally hit the debate stage for a rematch. While voters contemplate which of the pair stands to lose more by going head to head, another candidate is working hard to try to join them – Robert F Kennedy Jr. The controversial independent candidate doesn’t even have the backing of his famous political family, but he’s polling nationally stronger than any third-party candidate has in decades. This week, Jonathan Freedland speaks to political analyst David Corn about which of the two frontrunners should be more worried by RFK Jr’s presidential campaign