The stage has now been set for a 2020 presidential election rematch this November after Donald Trump and Joe Biden secured their party nominations.
The former president won primaries in Georgia, Mississippi and Washington and the caucus in Hawaii on Tuesday night, taking him over the threshold of 1,215 delegates needed to secure the Republican party nomination.
Mr Biden also secured the Democratic nomination for president after winning the primaries in Mississippi, Washington and Georgia.
As the nation readies for a 2020 rematch, the two candidates appear to be neck-and-neck among voters in the first major national poll released since they secured the nominations.
In a new Reuters/Ipsos poll, which closed on Wednesday, Mr Biden inched past Mr Trump with a marginal lead of 39 per cent to 38 per cent.
This came after a USA TODAY/Suffolk University poll, carried out between 8 and 11 March after the State of the Union and just one day before Mr Trump and Mr Biden officially secured the required delegates, found that 40 per cent of voters supported Mr Trump and 38 per cent Mr Biden when presented with the two candidates.