Democratic presidential contender Bernie Sanders won a nominating contest in Alaska on Saturday, chipping away at front-runner Hillary Clinton's commanding lead in the race to pick the party's candidate for the White House.

Sanders was aiming for a sweep of three Western states - Washington and Hawaii also are holding contests - that would generate more momentum in his bid to overtake Clinton and help stave off calls from Democratic leaders that he should wrap up his bid in the name of party unity.

Clinton, the former secretary of state, has increasingly turned her attention toward a potential Nov. 8 general election showdown against Republican front-runner Donald Trump, claiming she is on the path to wrapping up the nomination.

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Heading into Saturday's voting, she led Sanders, a U.S. senator from Vermont, by about 300 pledged delegates in the race for the 2,382 delegates needed to win the nomination at July's convention. Adding in the support of superdelegates - party leaders who are free to back any candidate - she has 1,690 delegates to 946 for Sanders.

Sanders needs to win up to two-thirds of the remaining delegates to catch Clinton, who will keep piling up delegates even when she loses under a Democratic Party system that awards delegates proportionally in all states.

But Sanders has repeatedly said he is staying in the race until the convention, pointing to the big crowds at his rallies and his impressive fundraising figures as proof of his viability.