Half of all voters in the US will "definitely not consider" voting for Donald Trump in November's presidential elections, a new poll has revealed. Overall, Hillary Clinton led Trump 39% to 36%.

The Morning Consult survey, which tested the ceiling of support for the presidential candidates, showed that 50% of respondents would not consider Trump to succeed Barack Obama, while 45% said they would definitely not back Hillary Clinton.

"It's not especially surprising that those numbers are so high because the two candidates are historically unpopular," the Morning Consult noted.

"But, given the challenge Republicans already face with the electoral map, Trump would almost certainly have to outperform Clinton in the popular vote, and that appears unlikely."

The poll showed that 35% of people would definitely vote for the Democratic nominee, while Trump lagged behind on 29%, highlighting the scale of the challenge to win the nationwide vote. Some 16% would at least consider voting for either Trump or Clinton.

Last week, the Wall Street Journal (WSJ) said the GOP nominee and his supporters are facing a "moment of truth". In a scathing editorial, the paper said if Republican backers "can't get Mr Trump to change his act by Labor Day, the GOP will have no choice but to write off the nominee as hopeless and focus on salvaging the Senate and House and other down-ballot races.

"As for Mr Trump, he needs to stop blaming everyone else and decide if he wants to behave like someone who wants to be President – or turn the nomination over to Mike Pence."

The Republican nominee overhauled his campaign team for the second time in two months last week. Trump's campaign manager, Paul Manafort resigned amid growing speculation over his ties to Ukrainian politics.

While Clinton appears to be in a strong position to win the White House, the survey showed she is more likely to lose votes than any other contender. More than 25% of those planning to back Clinton would also be willing to consider Green Party candidate, Jill Stein, while only 14% of Trump supporters would be inclined to do the same.

As the race for the White House enters the final stretch, figures showed that Clinton has amassed significantly more financial firepower than her Republican rival. As of the end of July, the Democrat had $140m (£107m) in the bank compared to Trump's $78m, the WSJ reported.

The figures are based on surveys of 2,001 voters on 16-17 August and 18-20 August. The margin of error in both polls is 2%.