Biden poised for boost as Democratic primaries begin in South Carolina

State holds party's first official primary under new schedule, with president polling at 70%

Joe Biden aims to build on recent momentum on Saturday, when South Carolina officially launches the race for the Democratic presidential nomination.

The US president received a boost last month when he won an unsanctioned primary election in New Hampshire without even appearing on the ballot. A grassroots write-in campaign ensured that he brushed aside his challengers Dean Phillips and Marianne Williamson.