America's Green Party candidate for the presidency has slammed both Hillary Clinton and Donald Trump for creating a culture of fear across the country and turning the presidential election into a "race to the bottom".

Dr Jill Stein said that whatever the eventual result of Tuesday's election, the voters would regret their choice and the future for America looks dark.

"It's a tipping point moment," the Harvard-educated medical doctor told The Telegraph. "There's so much angst out there, there's just so much fear and fear campaigning."

She said she was targeting five per cent of the vote on Tuesday - a marker that, if reached, would mean $8-10 million in public funds for the 2020 election and would guarantee the party being on the ballot in most states.

She is currently polling at 4 per cent, according to a poll on Thursday by CBS News/NY Times, although polling for third party candidates is historically far higher than actual results. Dr Stein won just 0.36 per cent of the popular vote in the 2012 presidential election.