In an interview with CBS News' Ed O'Keefe on "Red & Blue" Thursday, Democratic National Committee chairman Tom Perez said a proposed rule change to limit the influence of so-called "superdelegates" in the presidential nominating process will "empower" the party's grassroots activists. Perez spoke to O'Keefe at the DNC's summer meeting in Chicago.

Superdelegates are Democratic Party dignitaries who can cast votes for candidates of their choosing at the party's presidential nominating convention. Critics of the superdelegate system say that they have the ability to ignore the will of primary voters and back establishment candidates.

Perez told O'Keefe that superdelegates have never decided the outcome of a Democratic primary. But "what they have done," he said, is affected Democratic voters' perceptions about the fairness of nominating contests.

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To remedy that, Perez is hoping the DNC passes a rule change that would forbid superdelegates from casting votes on the first ballot at the convention unless the nominee has already been decided. The rule change, he said, would give additional leverage to grassroots activists and the party's rank-and-file, and allow the Democrats to "earn trust back."

"We think it's so important that we return power to the grassroots," Perez said.

Perez and O'Keefe also discussed a recent report of a cyberattack against the DNC. The attack, Perez said, turned out to be a "false alarm," but defended the party's vigilance against cyber threats.

"We have to be prepared every single day," Perez said. He also said the federal government had not been as helpful as it could be in minimizing the chances of an attack. "They're going after our democracy," he said of foreign hackers. "This shouldn't be a partisan issue."

Describing the upcoming midterm election as the "most important" of his lifetime, Perez criticized President Trump for a "culture of corruption" in Washington, D.C. He also said Mr. Trump was devoting his energies to building a "bigger swamp" and ignoring his responsibility to improve Americans' lives.

However, Perez sidestepped a question about whether a vote for Democrats in November is a vote for Mr. Trump's impeachment. He said instead that a vote for Democrats is a vote for "healthcare for all," protecting people with preexisting conditions, defending the rights of workers to unionize and taking insurance companies to task.

Asked about allegations against Rep. Keith Ellison, the deputy DNC chair currently running for attorney general of Minnesota, Perez said that an investigation is underway. Ellison's ex-girlfriend, Karen Monahan, has alleged that the Democrat abused her during their relationship, a charge Ellison denies.

Ellison was not present at the DNC meeting, which Perez said was because he was busy campaigning. Perez said that he is in touch with Ellison, and takes all allegations of sexual misconduct "very, very seriously." Democrats, he said, "have never hesitated" to hold people accountable, which he said was a marked contrast from Republicans under Mr. Trump.