The polling, which began on Friday, a day after Trump was indicted, found that 81% of self-identified Republicans said politics was driving the case, reflecting the deep polarization of the US electorate.

Some 62% of respondents including 91% of Democrats and 35% of Republicans, said it was believable that Trump illegally stored classified documents at his home in Florida as alleged by prosecutors.

Some 43% of self-identified Republicans said Trump was their preferred candidate, compared to 22% who picked Florida Governor Ron DeSantis, Trump's closest rival.

The rest of the Republican field, which includes former Vice President Mike Pence who declared his candidacy last week, had low single-digit levels of support.