The former president won the Missouri, Michigan and Idaho caucuses comprehensively, continuing his clean sweep of states so far.

Mr Trump, 77, told supporters at a rally in Virginia that he was “on a rocket to the Republican nomination”. He is on track to secure it next week.

His last remaining rival in the race, former South Carolina Governor Nikki Haley, is still seeking her first victory and is without a clear path to the nomination given Mr Trump’s commanding lead.

He is projected to win all of the delegates available in Missouri and all in Idaho, according to the BBC’s US partner CBS news, as well as all of those remaining in Michigan. A third of delegates in that state were awarded earlier this week after a primary that Mr Trump won.

Delegates represent their state or district at the respective party’s national convention, and decide who its presidential nominee will be. So far Mr Trump has secured 247 Republican delegates, according to CBS, far more than Ms Haley’s 24.

In the Virginia capital of Richmond on Saturday, thousands queued for several hours to hear Mr Trump speak. He vowed to “win big” on Tuesday, when 15 states will choose their presidential candidate on a day that could put him within striking distance of the nomination.