According to CBS, Biden has emerged victorious in Democratic nominating contests in 12 states, including Iowa, where voters cast ballots by mail.

Biden has won Democratic nominating contests in 13 states – plus Iowa, where people voted by post – according to CBS, which is BBC’s US partner network
Trump have won 10 Republican nominations.

Victorious candidates are being awarded delegates – of which they need a certain number to get their party’s official nod to run for president – which would further consolidate Trump’s strong lead over Nikki Haley in the overall GOP standings