In a warning shot to Hillary Clinton, Bernie Sanders on Sunday trounced the Democratic front-runner in the crucial presidential caucuses in Washington, Alaska and Hawaii, making "inroads" into her substantial lead in the race for the party's nomination for the White House.
Sanders, 74, won Washington state by getting more than 72 per cent of the total votes counted. In Alaska, he received more than 80 per cent of the votes. He also won in Hawaii with a big margin over the former secretary of state.
For Clinton, 68, who continues to lead in the delegate count and her path to the White House appears to be much easier as compared to Sanders, a defeat in the crucial state of Washington is seen as a major setback.
Home to major iconic US companies like Boeing, Microsoft and Starbucks, Washington state has more than 100 delegates, a large chunk of which has now gone to Sanders.
"We knew things were going to improve as we headed west," Sanders said at a rally in Madison, Wisconsin.
"We are making significant inroads in ... Clinton's lead ... We have a path toward victory," the Vermont Senator told his supporters.
Clintons, including the former president Bill Clinton, and their daughter Chelsie Clinton, spend quite a bit of time in Washington.
In Alaska, which has 16 delegates at stake, the wife of Sanders campaigned for a few days.
"We knew things were going to improve as we headed West," Sanders said.
"With your help we're going to win right here in Wisconsin," he said. "So don't let anyone tell you we can't win the nomination, or win the general election. We're going to do both of those things."
He said the momentum building behind his campaign comes from big crowds at rallies, from overwhelming victories, from record turnouts at caucuses and primaries, from a grassroots campaign taking on the political establishment and from more than two million supporters who donated less than USD 30 apiece on average.
"We are on a path toward victory," Sanders said in Wisconsin, where the Democratic primaries are scheduled for April 5. There are 86 pledged delegates at stake in Wisconsin.
To become a Democratic party presidential nominee, Clinton or Sanders need at least 2,382 delegates of the total 4,763 delegates including 712 super delegates, who are party office bearers and are not elected as part of the presidential primaries. Super delegates are independent and are free to vote to any of the candidates.
So far, Clinton leads the race to the White House in the Democratic party as she has 1,703 delegates. This includes 1,234 delegates she won during the presidential primaries and 469 super delegates who have said they would vote for her.
On the other hand, Sanders has 985 delegates to his kitty. These include 956 delegates won by him and 29 super delegates, who have pledged support to him.
Clinton's campaign privately acknowledged that Saturday would be a good one for Sanders, and her efforts in Washington were aimed mostly at trying to keep the race relatively close, as delegates are distributed proportionally.
The size of Sanders's margins on Sunday served as a warning shot to Clinton.
Washington and Alaska had always looked to be favourable territory for Sanders, because they are predominantly white and rural population. Clinton had campaigned in Washington after losing to Barack Obama by about a 2-1 margin in 2008.
Even though Wisconsin could be fertile territory for Sanders on April 5, Clinton is poised to do well in her home state of New York on April 19 with its 247 pledged delegates.
She also faces favorable territory in the upcoming Super Tuesday contest on April 26 when Pennsylvania, Connecticut, Delaware, Rhode Island and Maryland voters head to the polls and nearly 400 pledged delegates are at stake.
"Bernie Sanders is not just earning the delegates he needs to win, he is showing DC's professional pundit class that, despite their premature eulogising of his progressive political revolution, the fight for the Democratic nomination is far from over," said Charles Chamberlain, executive director, Democracy for America.