Democratic presidential candidate Hillary Clinton on Monday (Nov 7) seeemd to have a 70 per cent chance of winning the White House race against her Republican rival Donald Trump, a top American pollster said on the eve of what is being described as the most crucial election in decades.

'Hillary Clinton has a 70 per cent chance of winning the election,' said FiveThirtyEight website's Nate Silver, who accurately predicted the outcome of 2008 and 2012 presidential elections.

'This is up from a 65 per cent chance two days ago, so Clinton, 69, has had a good run in the polls in the final days of the campaign,' he said.

Clinton's projected margin of victory in the popular vote has increased to 3.5 per cent from 2.9 per cent, Silver said.

In the 19 latest polls taken into account by the poll, Clinton is leading in 17 polls while Trump, 70, leads in just two polls.

Clinton's poll margin ranges from six per cent to two per cent, while Trump's ranges from two to five per cent.

'Seven of the 19 polls have Clinton leading by 4 points; another four have her ahead by 3 points, then we have a smattering of 1s, 2s and 6s, along with two pollsters, IBD/ TIPP and Los Angeles/USC Dornsife, who still have Trump ahead.

'On average, Clinton leads by 2.9 points in the polls, although the highest-rated pollsters have her a bit higher at 3.8 points, on average. As is usually the case, the range of national polls closely matches the FiveThirtyEight popular- vote forecast,' Silver said.

On the eve of the elections, Clinton had a lead of 2.9 percentage points over Trump in the websites average of polls.