Democratic National Committee Chairman Tom Perez found himself on defense Sunday responding to criticism that his party's lawsuit against Russia, President Trump and other 2016 campaign figures is a "sham" that contradicts his push to let Special Counsel Robert Mueller complete his probe.

“I don't know when … Mueller's investigation is going to end,” Perez said Sunday on NBC’s “Meet the Press.”

He also argued the deadline for filing such a suit was fast approaching and claimed he feared similar collusion could materialize in this year’s elections, in which Democrats are trying to take control of the House.

“I'm worried about these midterm elections because they did this (in 2016) with impunity,” Perez continued. “We had people on my team at the DNC who got death threats. And do you know what, when you try to do that to our team, yeah, I'm going to punch back. I'm punching back not only for my colleagues. I'm punching back for democracy.”

The suit filed Friday seeks a jury trial and damages in connection with the 2016 White House race in which Russian operatives purportedly hacked the DNC’s computer and phone systems, exposing efforts to help Hillary Clinton win the party’s presidential nomination over primary rivals. The content of the published emails were seen as damaging Clinton in the general election.

The 66-page suit also names as defendants Donald Trump Jr. and Trump son-in-law Jared Kushner as well as WikiLeaks and site cofounder Julian Assange.

“No one is above the law,” the suit argues. “In the run-up to the 2016, Russia mounted a brazen attack on American Democracy. The open salvo was on the DNC. Russia then used this stolen information to advance its own interest -- destabilizing the U.S. political system, denigrating the Democratic presidential nominee and supporting the campaign of Donald J. Trump, whose policies would support the Kremlin. … In the Trump campaign, Russian found a willing and active partner in the effort.”

Law professor Alan Dershowitz told Fox News this past weekend that the suit’s allegations against Russia and the Republican Party “will probably be dismissed,” though the case might have some standing in its pursuit of the alleged hackers. (Dershowitz also acknowledged that he briefly represented Assange several years ago.)

Trump and Brad Parscale, named as the 2020 Trump presidential campaign manager, have criticized the suit.

“So funny, the Democrats have sued the Republicans for Winning. Now he R’s counter and force them to turn over a treasure trove of material, including Servers and Emails!,” Trump tweeted Saturday.

Parscale tweeted Friday: “How would you describe the DNC and their last-ditch effort to revive the witch hunt with a lawsuit? Sham, bogus, corrupt, desperate, frivolous…”

Perez, who also defended the case on ABC’s “This Week,” said Sunday that Clinton was not consulted about the suit and defended the DNC spending on legal fees while reportedly at least $6 million in debt.

“We can't afford not to do this,” he said. “It's hard to win elections when you have interference in elections. We've been winning elections. We know how to walk and chew gum.”