Republican presidential nominee Donald TrumpDonald John TrumpTrump says he will 'temporarily hold off' on declaring Mexican drug cartels as terror organization House Judiciary Committee formally receives impeachment report Artist behind gold toilet offered to Trump sells banana duct-taped to a wall for 0,000 MORE's campaign chairman said Sunday that the Democratic National Committee's (DNC) leaked emails show the party favored presumptive presidential nominee Hillary ClintonHillary Diane Rodham ClintonYang expands campaign with senior hires for digital operations Top GOP legislator in California leaves party GOP senators request interview with former DNC contractor to probe possible Ukraine ties MORE from the start. 

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"What's in those emails show it was clearly a rigged system," Paul Manafort said on ABC's "This Week."

"Bernie SandersBernie SandersDemocratic strategist: 'Medicare for All' exposes generational gap within party Yang expands campaign with senior hires for digital operations Biden: All-white debate not representative of party, but 'you can't dictate' nominee MORE never had a chance, and frankly, I think you're going to see some of that resentment boil over this week [at the Democratic National Convention] in Philly." 

Emails from within the DNC leaked by WikiLeaks Friday showed party officials privately planned how to undermine the Vermont senator's presidential campaign. 

In one May 21 email, DNC press secretary Mark Paustenbach writes to communications director Luis Miranda about planting a narrative to the media that Sanders’s “campaign was a mess.”

"The establishment and the special interests picked their candidate, Hillary Clinton, and made sure nothing the people were going to do or say were going to interfere with her selection," Manafort said Sunday.