More US voters were bothered by Mr Donald Trump's treatment of women than by Mrs Hillary Clinton's use of a private e-mail server during her tenure as Secretary of State, two of the most talked about topics in the presidential campaign, exit polls show.

Asked about Mrs Clinton's use of private e-mail, 44 per cent of voters said it bothered them a lot and 62 per cent said it bothered them either some or a lot, Wall Street Journal reported, citing early national exit-poll results from Edison Research.

About 37 per cent said it bothered them not much or not at all, the poll showed.

Asked about Mr Trump's treatment of women, 51 per cent of voters said it bothered them a lot and 71 per cent said it bothered them some or a lot. Only 28 per cent said it bothered them not much or not at all.

In exit polls published by CNN, most voters said they had made up their minds well in advance, with 88 per cent of those surveyed saying that they had decided on who to vote for by October.

Only 12 per cent said they came to a conclusion only in the last week or last few days.

In preliminary national exit poll results reported by ABC News, 54 per cent of voters see Mrs Clinton unfavourably, while the figure was 61 per cent for Mr Trump, revealing the extent of how unpopular both candidates are.

Substantial numbers also say both Mrs Clinton and Mr Trump are not honest and trustworthy - 59 per cent in Mrs Clinton's case and 65 per cent in Mr Trump's. It's unprecedented even to ask this question in an exit poll, according to ABC.

Mrs Clinton does better, Mr Trump less well, on both qualifications and temperament, said the network. Fifty-three per cent of voters say she's qualified for office and 56 per cent feel she has the right personality and temperament for the job. Those decline to 37 per cent and 34 per cent for Mr Trump, respectively.