WASHINGTON (REUTERS) - Former US vice-president Joe Biden is the early leader for the 2020 Democratic Party nomination, a Reuters/Ipsos Election Day opinion poll found, in a field likely to quickly take shape as candidates seek to challenge Republican President Donald Trump.
Mr Biden received 29 per cent of the support.
Senator Bernie Sanders, an independent who made an unsuccessful run for the Democratic nomination in 2016, finished second in the hypothetical field with 22 per cent. The rest of the poll was tied between Senators Cory Booker, Elizabeth Warren and Kamala Harris.
All of the Democrats fared well in a popular vote hypothetical match-up against Mr Trump.
Before a single dollar has been spent on election ads or campaign rallies, the poll found Mr Biden scored best in a hypothetical match-up, beating Mr Trump 51 per cent to 39 per cent in the popular vote.
The poll found Mr Sanders, Mr Booker and Ms Harris would also defeat Mr Trump nationally if the election were held today.
Mr Trump did the best against Mr Booker, losing by only 4 percentage points in the hypothetical popular vote.
In 2016, Democrat Hillary Clinton won the popular vote by nearly three million ballots, but lost the presidential election to Mr Trump, who won the state-by-state Electoral College vote.
Opinion polls at this early a stage tend to be largely dominated by those with the most widespread name recognition.
Several polls after the 2014 congressional midterm elections found Mr Jeb Bush, who ultimately lost his bid for the Republican nomination, to be the front runner. Few polls even included Mr Trump.
On the Republican side, 65 per cent of Tuesday's midterm voters said they would renominate Mr Trump to represent their party. Another 11 per cent said they would prefer Vice-President Mike Pence and 12 per cent said they did not know who should be the nominee.
The poll was conducted online on Tuesday and based on responses from 38,196 people who voted in 37 states.
The poll is ongoing and will be updated as the vote is tallied.