NEW YORK - Republican presidential front-runner Donald Trump on Sunday suffered a double blow as he lost to rivals Senators Ted Cruz and Marco Rubio in polls in the US capital and Wyoming, suggesting the race for the presidential nomination for the 2016 US election is tightening.

Trump, the controversial billionaire businessman may be ahead in national polls and in party delegates, but he was easily defeated in the Republican caucus in Washington, the US capital city.

Senator Rubio, from Florida, earned 37.3 per cent of the vote against 35.5 for Ohio Governor John Kasich. Trump was third, with 13.8 per cent support.

Senator Rubio won 10 of the 19 delegates at stake, while Governor Kasich walked away with the other nine, leaving none for Trump.

But Trump is said to be the favourite at this point of time as he has the maximum number of 460 delegates followed by Cruz (367), Rubio (153) and the Ohio Governor John Kasich 63. To win the party’s presidential nominee, the candidates need to have the support of 1,237 delegates out of a total of 2,472 delegates.

Rubio has so far won Minnesota, Puerto Rico and District of Columbia. However, he has put all at stake in his home state of Florida where the primary is scheduled for March 15. It would be very difficult for him to continue his presidential ambition with a loss in Florida.

The same is true for Kasich, who is fighting a battle for survival in the race in Ohio. Cruz is the only Republican candidate to have defeated Trump in more than half a dozen states. He handsomely defeated Trump in Wyoming. Cruz won nearly two-thirds of the total vote in Wyoming Caucuses.

Cruz crushed Trump by winning 66.3 per cent of the ballots, far ahead of Rubio, his nearest rival, who earned 19.5 per cent of the vote. Trump came in third with a measly 7.2 per cent.

On the Democratic side, former Secretary of State and front-runner Hillary Clinton won in the first ever Democratic Party caucus on the Northern Mariana Islands, a US possession deep in the Pacific Ocean.

She won four delegates, while her rival, Senator Bernie Sanders, won two, US media reported. Cruz also picked up one delegate in Guam while the island’s five other delegates were uncommitted.