President Joe Biden has stressed the need for divided Americans to come together as he addressed the nation, after Donald Trump was shot in an assassination attempt.    As former President Trump heads to the Republican National Convention to receive the party's nomination for the upcoming election, will he seek to 'lower the temperature' or capitalise on the polarisation of the nation?   On today's Daily, Niall Paterson is joined by our US correspondent James Matthews to explore how realistic President Biden’s calls for unity are during this heated election campaign.   Plus, Dr James Cooper, associate professor of history and American studies at York St John University, explains why political violence is nothing new in the US.    Producer: Emma Rae Woodhouse, Rosie Gillott, Soila ApparicioEditor: Philly BeaumontPodcast Promotions Producer: David Chipakupaku