Elizabeth Warren & Bernie
© REUTERS/Yuri GripasSenator Elizabeth Warren and Senator Bernie Sanders promote universal healthcare in Washington on September 13, 2017
Senator Elizabeth Warren said she agreed with the suggestion, after a report claimed that Ms Clinton had controlled multiple aspects of the party's infrastructure.

Former Democratic National Committee (DNC) chair Donna Brazile wrote in a report for the Politico that Ms Clinton's campaign had assumed control of key fundraising aspects of the party before she went on to defeat Bernie Sanders.

The DNC seeks to elect Democrats nationwide, not just to the White House.

The report seemed to bolster critiques from Sanders supporters who have long argued the Democratic establishment undermined their insurgent candidate in favour of Ms Clinton, who had built deep ties within the party over her years in politics.

In an interview with Ms Warren, who like Mr Sanders represents the party's farther-left progressive wing, CNN's Jake Tapper asked point-blank if the Massachusetts Democrat agreed "with the notion that it was rigged".

"Yes", Ms Warren replied.

Calling the arrangement detailed in Ms Brazile's report "a real problem", Ms Warren said Democrats needed to "hold this party accountable" or risk alienating its constituents. She said that would be the paramount challenge for recently elevated DNC chair Tom Perez.

"You have got to put together a Democratic Party in which everyone can have confidence that the party is working for Democrats rather than Democrats are working for the party", Ms Warren said, describing her message for Mr Perez.

"Either he's going to succeed by bringing Bernie Sanders and Bernie Sanders representatives into this process and they're gonna say 'it's fair, it works, we all believe it', or he's going to fail", Ms Sanders said. "And I very much hope he succeeds. I hope for Democrats everywhere, I hope for Bernie and for all of Bernie's supporters that he's going to succeed".