WATCH: Russia Is Helping Trump Become President, Says Clinton Campaign Manager

Robby Mook, Clinton's campaign manager, raised questions about whether Russians may have had a hand in the hack attack, and were interested in helping Trump, who has offered praise for Russian President Vladimir Putin.

"What's disturbing to us is that experts are telling us that Russian state actors broke into the DNC, stole these emails and other experts are now saying that Russians are releasing these emails for the purpose of helping Donald Trump," he said on CNN's "State of the Union."

"I don't think it is coincidental that these emails were released on the eve of our convention," he said.

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Trump campaign manager Paul Manafort said the Clinton camp was trying to distract from its party discord ahead of the convention.

"Well, it's pure obfuscation on the part of the Clinton campaign," Manafort said on ABC. "What's in those emails show that it was a clearly rigged system, that Bernie Sanders - Sanders never had a chance."