Donald Trump easily won the Republican caucuses in Michigan on Saturday, where the party has been riven by infighting that some Republicans fear could hurt his campaign in the key battleground state as he gears up for the general election in November.

The former U.S. president also won the Missouri and Idaho Republican caucuses on Saturday, according to Edison Research.

In all three states Trump trounced Nikki Haley, his last remaining rival for the Republican presidential nomination, moving him closer to becoming his party's White House standard-bearer and a likely general election rematch with President Joe Biden, a Democrat.

In Michigan, Trump beat Haley in all 13 districts taking part in the nominating caucuses, according to the state Republican Party.

Overall, Trump won with nearly 98% percent support: 1,575 votes to just 36 for Haley.

Pete Hoekstra, the Michigan Republican Party's chair, called it an 'overwhelming, dominating victory.'

More than 1,600 party insiders participated in the presidential caucus in the western Michigan city of Grand Rapids, where they were choosing delegates for Trump or former U.N. Ambassador Haley for the party's national nominating convention in July.

Haley is fast running out of time to alter the course of the Republican nominating race. Next up is Super Tuesday on March 5, the biggest day in the primaries, when 15 states and one territory will vote.

With victories in Iowa, New Hampshire, Nevada, the U.S. Virgin Islands, South Carolina, and now Michigan, Missouri and Idaho under his belt, Trump is far and away the frontrunner in the race, with Haley hanging on thanks to support from donors keen for an alternative to the former president.

For this election cycle, Michigan Republicans devised a hybrid nominating system, split between a primary and a caucus.

Trump won the primary convincingly on Tuesday, securing 12 of 16 delegates up for grabs. He took all of Michigan's remaining 39 delegates at stake on Saturday.