After three big wins out west, Democratic presidential hopeful Bernie SandersBernard (Bernie) SandersHow to stand out in the crowd: Kirsten Gillibrand needs to find her niche Biden, Sanders edge Trump in hypothetical 2020 matchups in Fox News poll O'Rourke tests whether do-it-yourself campaign can work on 2020 stage MORE said he thinks many of the party's superdelegates who have pledged to rival Hillary ClintonHillary Diane Rodham ClintonHow to stand out in the crowd: Kirsten Gillibrand needs to find her niche Ex-Clinton aide: Dems should make 2020 'about integrity' Trump mounts Rust Belt defense MORE will switch to his side.

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"I think the momentum is with us," Sanders said on CNN's "State of the Union" with Jake Tapper on Sunday. "A lot of these superdelegates may rethink their positions with Secretary Clinton."

The Vermont senator swept Saturday's Democratic contests in Washington, Alaska and Hawaii, easily winning the majority of the 142 pledged delegates in those states. The biggest prize of the day was in Washington, which offered 101 delegates to be split up on a proportional basis.

The latest delegate counts still put Sanders behind Clinton, however, with 975 pledged delegates to herĀ 1,243.

In addition, 469 superdelegates back Clinton, while only 29 support Sanders.

Sanders on Sunday said those superdelegates may begin to see the "reality" that he's the best candidate to beat GOP front runner Donald TrumpDonald John TrumpHow to stand out in the crowd: Kirsten Gillibrand needs to find her niche Countdown clock is on for Mueller conclusions Omar: White supremacist attacks are rising because Trump publicly says 'Islam hates us' MORE.

"I think when they begin to look at reality, and that is that we are beating Donald Trump by much larger margins than Secretary Clinton," Sanders said. "And then you've got superdelegates in states where we win by 40 or 50 points. I think their own constituents are going to say to them, 'Hey, why don't you support the people of our state and vote for Sanders?'"

This report was updated at 9:31 a.m.