Donald Trump said on Tuesday that he will not become a dictator if he becomes U.S. president again except "on day one", after warnings from Democrats and some Republicans that America was in danger of becoming an autocracy if he wins the 2024 election.

Republican presidential candidate Trump had to be asked twice during a televised town hall event in Iowa to deny that he would abuse power to seek revenge on political opponents if re-elected to the White House.

“No. No. Other than day one,” Trump said when asked to deny he would become a “dictator” if he wins the November election.

Trump said on the “day one” he referred to, he would use his presidential powers to close the southern border with Mexico and expand oil drilling.

Trump, seeking a second White House term in a likely election re-match with Democratic President Joe Biden, has frequently promised “retribution” on political opponents if he gains power again.