US election 2016: Marco Rubio wins Puerto Rico primary as hard-left Sanders takes Maine
WHITE House hopeful Marco Rubio has swept to victory in the Republican Party's Puerto Rico primary tonight.
Republican hopeful Marco Rubio and Democrat Bernie Sanders triumphed tonight
The Florida senator thrashed his rivals on the island, picking up 73.8 per cent of the votes compared to Donald Trump's 13.6 per cent.
He is expected to win all 20 delegates determined by the primary, just a day after Trump urged him to exit the race.
And hard-left Democratic candidate Bernie Sanders picked a win in Maine, a day after beating former First Lady Hillary Clinton in Kansas and Nebraska.
This primary will demonstrate the Hispanic vote is important
Jenniffer Gonzalez, chairman of Puerto Rico's Republican Party, said: "The numbers are overwhelming.
"This primary in Puerto Rico will demonstrate the Hispanic vote is important."
Residents of Puerto Rico are not eligible to vote in the Presidental election in November but can take part in the party primaries.
Marco Rubio shakes hands with supporters in in Toa Baja
Sanders and Clinton took part in a televised debate in Flint, Michigan as Republicans went to the polls in Maine.
The debate was held to highlight the city's public health crisis from contamination of its water supply, with both candidates condemning local officials.
Sanders branded it a "disgrace beyond belief" while Clinton said: "People should be held accountable, wherever that leads. There has to be absolute accountability."
Sanders and Hillary Clinton debated the water crisis in Maine
Despite his win, Sanders could struggled erasing Clinton's lead of about 200 delegates who will choose the nominee in mid-July.
She will keep gathering delegates even in those states she loses because the Democratic race awards delegates in each state proportionally.
But the Vermont senator remains confident he can win, saying: "We have the momentum. We have a path toward victory. Our campaign is just getting started."