Donald Trump has swept to Republican victory by peddling rhetoric of a wrecked economy, a rigged political system and the "danger" of terrorists and illegal immigrants.

His key foreign policy involves keeping foreigners out, by building a wall along the US-Mexico border.

But a new survey by Public Policy Polling has discovered that 31 per cent of Trump supporters would be in favour of - or, at least, would not be against - building another wall along the coast of the Atlantic Ocean to deter Muslim immigrants from the Middle East.

The support breaks down to 18 per cent of people in favour, while 13 per cent were “not sure”.

A little more than half his supporters - 52 per cent - oppose the idea.

The poll also found that voters consider Mr Trump more favourable than junk mail, the Bubonic plague, bed bugs and mosquitoes.

“One reason Trump's campaign may be struggling is that voters just don't buy into the premise that the United States is a dangerous country,” the poll read, which surveyed 881 likely voters between 26 and 28 August.

Only 26 per cent of voters believe the US is a dangerous country.

The numbers come one day before Mr Trump is due to give a key speech on his immigration policy, a topic he has pushed to win the votes of the white middle class.

The speech was rescheduled from last week, causing speculation that he might be softening his stance on plans to deport millions of illegal immigrants, carry out "extreme vetting" and impose a temporary ban of all Muslims entering the US.

Mr Trump has also been focused on reaching out to Latino and African American voters.

Loading....

He guaranteed last week that he would have “95 per cent of the African American vote” within four years. One tactic was to politicise violence, claiming that the killing of Dwyane Wade’s cousin, Nykea Aldridge, in Chicago would act as an incentive for African Americans to vote for President Trump.

Thus far Mr Trump has low favourability ratings with ethnic minorities, however.

Only 13 per cent of Latinos and African Americans believe that Mr Trump “actually cares about them”, according to the poll.

The majority of voters - 67 per cent - also want Mr Trump to release his tax returns.

Mr Trump’s 37 per cent of the vote lags rival Hillary Clinton’s 42 per cent, according to the poll, but the Republican has beaten several other personalities and pundits, including the disgraced Olympic swimmer Ryan Lochte, the right-wing commentator who was “roasted” on Comedy Central, Ann Coulter, and Fox News-turned-Trump adviser Sean Hannity.