Donald Trump crushed his Republican rivals in Indiana, US networks projected, bringing him dramatically closer to outright victory in his party's presidential nomination race and dashing the hopes of a movement bent on stopping him.
"Thank you Indiana!" Trump tweeted as the race was called in his favour yesterday.
Based on 13 per cent of precincts reporting, the billionaire frontrunner took 53.8 per cent of the vote, streets ahead of his nearest rival Ted Cruz on 33.9 and John Kasich on 9.4 per cent.
The Democratic race between Hillary Clinton and Bernie Sanders was still too early to call in the Midwestern state, but early voting results showed the former secretary of state with a razor-thin lead against her rival.
Both Trump and Clinton were hoping Indiana would put them one step closer to locking up the White House nominations -- and their likely November showdown.
But yesterday's contest is seen as a day of reckoning for the "stop Trump" movement led by Cruz -- who has performed well in primaries dominated by conservative and evangelical voters, and was given a strong chance in Indiana.
Cruz was hoping to use Indiana as a firewall, blocking Trump from receiving the 1,237 delegates necessary to secure the nomination at the Republican convention in Cleveland in July.
"Lyin' Ted Cruz consistently said that he will, and must, win Indiana. If he doesn't he should drop out of the race-stop wasting time & money," Trump tweeted.
The frontrunner has so far amassed 1,002 delegates, according to CNN's tally. Cruz is at 572 delegates, while Ohio Governor John Kasich trails with 156.
If Trump sweeps Indiana's 57 delegates, the Cruz camp has admitted it faces an extremely steep road ahead.
