Fewer than half of voters who cast presidential ballots on Tuesday say they made their choice out of a strong preference for their candidate.

Preliminary results of the exit poll, conducted for The Associated Press and television networks by Edison Research, found both Republican Donald Trump and Democrat Hillary Clinton are viewed unfavourably by a majority of the presidential electorate.

And a majority of the electorate also distrusts each of them.

Six of 10 voters say they are somewhat bothered or bothered a lot by Clinton's use of a private email server while secretary of state.

And more than seven out of 10 presidential voters say they are irked by Trump's treatment of women.