Donald Trump won the first 11 primary elections, including Texas, as results came in from the 15 "Super Tuesday" states in the race for the Republican presidential nomination.

The former president, who is bidding for a sensational White House comeback after being unseated by Democrat Joe Biden in 2020, could claim a clean sweep of states Tuesday on the way to the Republican Party nomination.

Alabama, Arkansas, Colorado, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas and Virginia were all called by US networks for Trump, who expressed thanks on his Truth Social site as counts continued in the other Super Tuesday states across the country.

His longshot challenger, former UN ambassador Nikki Haley, has failed to be a significant obstacle in Trump's path to the nomination, but has so far refused to drop out of the race.

In the Democratic nomination contest, as expected, Biden won all of the 13 states to be called by US networks, though he was projected to lose to little known challenger Jason Palmer in the small Pacific Ocean territory of American Samoa.

Polling averages from RealClearPolitics show Trump two points ahead of Biden in a one-on-one match-up in the November election.