Bernie Sanders made a clean sweep of Democratic election contests in Alaska, Hawaii and Washington, although he barely dented the formidable lead enjoyed by frontrunner Hillary Clinton in the battle for the party's presidential nomination. US news networks showed Sanders winning by wide margins Saturday's caucus votes in all three western states.
In Washington - the biggest prize with 101 delegates up for grabs - Sanders won with an estimated 72.1 percent, against 27.7 for Clinton.
In Hawaii, 71 percent of Democratic caucus-goers supported Sanders, against 29 percent for Clinton. In Alaska, Sanders' margin of victory was 79.2 percent, against 20.8 percent for Clinton.
The 74-year-old Vermont senator celebrated his victories via Twitter late Saturday.
"Thank you, Alaska! Together we are sending a message that this government belongs to all of us," he wrote.
"Washington, thank you for your huge support! It is hard for anybody to deny that our campaign has the momentum."
Sanders maintains he has a path to winning the nomination and is plowing ahead state by state, ahead of another round of primary and caucus contests next month.
But the delegate math still dramatically favours Clinton, who headed into Saturday's contests with a big lead among pledged delegates and an even larger advantage when party officials known as "superdelegates" are factored into the equation.
At a campaign rally in the midwestern state of Wisconsin, Sanders declared - despite pundits' negative predictions - that the tide was now turning in his favour. "We knew things were going to improve as we headed west," he said to cheers.
"We are making significant inroads in Secretary Clinton's lead and we have... a path toward victory." "This is what momentum is about," Sanders told his supporters.
"Don't let anybody tell you we can't win the nomination or win the general election. We're going to do both of those things."
Going into Saturday, Clinton had already amassed 1,711 delegates, including super-delegates who are unelected by voters, compared to 952 for Sanders, according to a CNN count.
To win the Democratic nomination at the July convention in Philadelphia, 2,383 delegates are needed.