Hillary Clinton holds steady with a 42 per cent share of voters, according to a new poll on Wednesday - but her popularity has hit a record low in a separate survey.

Clinton still comfortably leads Donald Trump, who has slipped a point to 37 per cent, the You Gov/Economist poll showed. Libertarian Gary Johnson has gained a point to 7 per cent, while the Green candidate Jill Stein is down one, at 3 per cent.

But despite Clinton's solid lead her popularity among the American people has plummeted.

The YouGov poll put Clinton's unpopularity ratings at a new high of 58 per cent, up five points. Trump came in at 64 per cent, up two points.

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Clinton at a fundraiser on Tuesday. Her and Trump's high unfavorability ratings make them the most unpopular candidates ever, according to an ABC News/Washington Post poll

Trump has lost a point to 37 per cent, trailing Clinton's 42 per cent, the You Gov/Economist poll showed

And a separate survey found that Clinton is now the most unpopular she has ever been in her 25 years in national public life, according to an ABC News/Washington Post poll.

Some 56 per cent of all adults now see the Democrat unfavorably, the poll found - a spike of 6 points in just three weeks.

And while Clinton by that measure is ahead of Donald Trump, who is disliked by 63 per cent of all adults, that gap virtually disappears among registered voters: 59 per cent of them do not approve of Clinton, against 60 per cent for Trump.

Clinton held her 42 percent share in the YouGov/Economist poll even as her popularity ratings have plummeted

As the November 8 presidential election closes in, Clinton remains dogged by reports on her private email server and of her ties to the Clinton Foundation while serving as secretary of state.

The most unpopular major party candidate ever seen in the ABC News/Washington Post poll before this election was George H. W. Bush. He was treading water at 53 per cent in July 1992, shortly before losing his re-election attempt.

Worryingly for Clinton, the poll said that her rise in unpopularity has been most evident among some of her key demographics: women, Hispanics, liberals and post-graduates.

Some 52 per cent of women now view Clinton unfavorably - an almost complete reversal of the presidential hopeful's ratings just last month, when 54 per cent viewed her positively.

Trump has actually grown less unpopular in recent weeks - his unfavorability ratings were at a dismal 70 per cent in June.

But the low approval ratings among both candidates is a cause for concern, particularly in terms of turnout on the day of election, pollsters say.

'Clinton and Trump’s unprecedentedly low ratings raise substantial uncertainties about voter turnout in the November election,' the poll said.

'The open question is whether they can motivate their potential supporters to show up to vote – either for them, or, as may be more likely, against their unpopular opponent.