Democratic presidential candidate Bernie Sanders addresses a rally Wednesday at the Santa Clara County Fairgrounds in San Jose, Calif. The senator's campaign is intently focused on a big win in the state on June 7, and has poured money into TV ads there.
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Democratic presidential candidates Sen. Bernie Sanders and Hillary Clinton stand together before the start of the Univision-Washington Post debate at Miami Dade College in Miami on Wednesday.
Democratic presidential candidates Sen. Bernie Sanders and Hillary Clinton take the stage before a Democratic presidential primary debate at the University of Wisconsin-Milwaukee on Thursday.
Sen. Bernie Sanders and former Secretary of State Hillary Clinton spar during a Democratic presidential primary debate hosted by MSNBC at the University of New Hampshire on Thursday.
Democratic presidential candidate, Sen. Bernie Sanders, I-Vt., gestures towards Democratic presidential candidate, Hillary Clinton during the NBC, YouTube Democratic presidential debate in Charleston, S.C., on Sunday.