After three big wins out west, Democratic presidential hopeful Bernie SandersBernie SandersOvernight Health Care: CDC approves Pfizer vaccine for adolescents aged 12-15 | House moderates signal concerns with Pelosi drug pricing bill | Panel blasts COVID-19 response Briahna Joy Gray: Warren not endorsing Sanders in 2020 was 'really frustrating' House moderates signal concerns with Pelosi drug pricing bill MORE said he thinks many of the party's superdelegates who have pledged to rival Hillary ClintonHillary Diane Rodham ClintonMore than half of eligible Latinos voted in 2020, setting record Fox News signs Trey Gowdy, Dan Bongino for new shows The Memo: GOP attacks bounce off Biden 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 TrumpWarren says Republican party 'eating itself and it is discovering that the meal is poisonous' More than 75 Asian, LGBTQ groups oppose anti-Asian crime bill McConnell says he's 'great admirer' of Liz Cheney but mum on her removal 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.