Nikki Haley wins the Republican presidential primary in Vermont

Republican presidential candidate former UN Ambassador Nikki Haley (David J Phillip/AP)

Former UN ambassador Nikki Haley scored a surprise victory on Super Tuesday, upsetting Donald Trump to win Vermont.

However, that victory will do little to dent Mr Trump’s primary dominance. The former president won 11 other states on Super Tuesday.

Mrs Haley is the last major rival to Mr Trump in a once-crowded primary field.

She has increasingly stepped up her attacks on the former president, arguing that if he clinches the party’s nomination, he will lose to US president Joe Biden in November.

On the Democratic side, Mr Biden also ran up the score with wins all around the country against only token primary opposition — all but cementing the long-expected November rematch between him and Mr Trump.