The Democratic Party filed a lawsuit Friday in Manhattan that alleges President Donald Trump's campaign worked with the Russians and WikiLeaks, a website that released thousands of hacked emails from people close to Clinton.
"During the 2016 presidential campaign, Russian Federation launched an all-out assault on our democracy, and it found a willing and active partner in Donald Trump's campaign", DNC Chairman Tom Perez said in a statement.
"This constituted an act of unprecedented treachery".
Some within the Democrats' own ranks disagreed with the lawsuit.
He says the campaign is prepared to leverage the discovery process to explore the inner workings of the DNC, including officials' emails.
Mr Trump has repeatedly denied the allegations, referring in a tweet this week to the "phony Russian Federation investigation where, by the way, there was NO COLLUSION (except by the Dems)".
In a statement, Parscale accused Democrats of filing the lawsuit to drum up donations for the party.
If the DNC wants "to be influential and important, it has to raise money", commentator Salam said.
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U.S. intelligence agencies previously concluded Moscow had tried to sway the election in Mr Trump's favour. "And I'm not very supportive of it".
If the lawsuit proceeds, the president and his campaign aides could be forced to disclose documents and submit to depositions that require them to answer questions under oath.
"Just heard the Campaign was sued by the Obstructionist Democrats", Trump said in a Twitter post on Friday. That litigation is still in progress.
Trump himself is not named as a defendant.
There is substantial overlap between the targets of the DNC lawsuit and the group of people known to be under investigation by Mueller.
A copy of the suit alleges the Trump campaign "gleefully welcomed Russia's help".
Trump tweeted that the DNC lawsuit could be "very good news", saying that his campaign "will now counter for the DNC Server that they refused to give to the Federal Bureau of Investigation", as well as Clinton's e-mails.
Techdirt, a site that deals with technology and legal issues, analyzed the suit and reported that the laws cited in the DNC suit generally indicate "pretty weak lawsuits", adding that some of the claims "are so outrageous that they would effectively make some fairly basic reporting illegal".