Hillary Clinton has lost the double-digit poll lead she had at the beginning of the week and now holds a slimmer four-point edge over her rival Donald Trump, a Washington Post/ABC News tracking poll showed Friday.

Clinton now has a 48 per cent slice of the vote, to Trump's 44 per cent among likely voters. On Sunday the ABC News poll showed her with a 12-point lead over the Republican.

Trump has gained ground among independents, at the expense of Libertarian Gary Johnson and Green Jill Stein who now have four per cent and one per cent respectively.

Independents now lean towards Trump over Clinton by a margin of 12 points, at 49 to her 37 per cent - a major swing from late last week when the Democrat had a slight edge. The subgroup has repeatedly swung between the two candidates throughout the fall.

Trump has also recovered ground among whites, especially those without college degrees and women.

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Donald Trump in Ohio on Thursday. He has gained ground over the past week against Hillary Clinton, the poll showed

Clinton was in North Carolina on Thursday with support from Michelle Obama. She now leads Trump by four points

White women have swapped their allegiance to the Republican by 48 per cent to 43 - a reversal from the 49 per cent to 43 per cent tilt in Clinton's favor which they had before.

The Clinton campaign has spent the week fending off a series of revelations from emails published by WikiLeaks and conservative group Citizens United.

The emails have shown how aides helped Bill Clinton amass tens of millions of dollars in speaker fees and engagements following his presidency. Others showed how Clinton associates tried to help billionaires and donors to the dynasty's charitable foundation get access to Hillary Clinton while she was secretary of state.

White women have swapped their allegiance to the Republican by 48 per cent to 43 - a reversal from the 49 per cent to 43 per cent tilt in Clinton's favor which they had before

Despite Trump's improving figures, six in 10 voters reckon that Clinton will win.

Still, only 27 per cent believe she will win 'easily', against 32 per cent who say her victory will be a close one. Just 9 per cent think Trump will win easily.

Clinton's campaign have been warning their supporters against complacency as the clock counts down to November 8.

Nate Silver's FiveThirtyEight blog has also calculated a slight drop in Clinton's chances since the beginning of the week.

In its 'polls-plus' forecast taking into account the economy and historical data, it estimates Clinton's chances at 78.9 per cent to Trump's 21 per cent - down from 83.9 per cent and 16.1 per cent on Sunday.

Trump's arguments that electoral system is rigged also seem to have lost momentum. Thirty-seven per cent of voters say fraud occurs 'very' or 'somewhat' often, down from 47 per cent in early September.

The poll was conducted by phone Oct. 23-26 and has a margin of error of plus or minus 2.5 points.