Sanders riding wave of momentum with 7 wins in 8 contests
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Democratic presidential hopeful Bernie SandersBernie SandersSunday shows - Russia standoff over Ukraine dominates Sanders says Biden can't count on him to support 'almost any' spending package compromise Sanders says Republicans are 'laughing all the way to Election Day' MORE's wave of momentum is growing, with another state win Tuesday in Wisconsin, his seventh victory of the past eight contests.

The results of Democrats voting abroad were announced on March 21. Then on March 22, Sanders won in Idaho and Utah, but not in Arizona. Four days later, he swept caucuses in Alaska, Hawaii and Washington. 

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The Vermont senator has been touting his success, claiming that he is beginning to convince Democratic superdelegates to support him instead of former Secretary of State Hillary ClintonHillary Diane Rodham ClintonNo Hillary — the 'Third Way' is the wrong way The dangerous erosion of Democratic Party foundations The Hill's Morning Report - Presented by Facebook - Democrats see victory in a voting rights defeat MORE.

"I think the momentum is with us," Sanders said the day after his caucus sweep. "A lot of these superdelegates may rethink their positions with Secretary Clinton."

March also saw the Sanders campaign set a new fundraising record, with the $44 million for the month, largely in small online donations.

But even with his momentum and financial resources, Sanders is still facing an uphill battle in the delegate race.

Sanders entered Tuesday trailing Clinton by 263 pledged delegates, according to The Associated Press. But because Democrats award their delegates proportionally, he would need to start winning states by large margins in order to catch up.

And even if he manages that, his chances may rest on winning over superdelegates, the majority of whom have backed Clinton. She has won over 469 superdelegates so far, while Sanders only has 31.