Former Deputy Assistant Attorney General John Yoo weighed in on a hot new topic on the 2020 presidential campaign trail.

Several Democratic contenders are talking up plans to overhaul the Supreme Court, with some offering proposals to add up to 15 more members, but Yoo said that would be a disaster.

“I think this is, of all the crazy ideas that you are seeing kicked around by the Democratic progressive, progressive aggressive candidates this is the worst one,” Yoo said on "Fox & Friends" Wednesday.

Candidates including Elizabeth Warren, D-Mass., Beto O’Rourke, D-Texas, Kamala Harris, D-Calif., Sens.Cory Booker, D-N.J., and Kirsten Gillibrand, D-N.Y., have all signaled a willingness to embrace expanding the Supreme Court if they become president. Progressive groups are putting their money behind the message, as part of an effort to tap into lingering liberal anger over President Trump's two nominees confirmed to the high court.

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“This is actually an effort to short circuit one of the Constitution’s restraints so that we don’t just have rule by the simple majority,” said Yoo.

“If you try to pack the Supreme Court you are just going to turn the Supreme Court and the judiciary just into another political actor and when Republicans get back in charge they’ll do the same thing, they will start adding more and more justices in the court to get the people they want there and soon the Supreme Court will just be like another branch of the legislature and not a serious small body that’s there to interpret the Constitution."

“I think this is, of all the crazy ideas that you are seeing kicked around by the Democratic progressive, progressive aggressive candidates this is the worst one.” — John Yoo, Former Deputy Assistant Attorney General

Neil Gorsuch was confirmed after former President Barack Obama's choice -- Judge Merrick Garland -- remained in the Senate without a hearing or vote during the 2016 election year.

Brett Kavanaugh's confirmation process was defined by allegations of sexual misconduct. Both were confirmed mostly along party lines.

Many Democrats think the solution would be to add more members while changing the rules for who can serve and for how long.

Among the proposals are rotating justices on and off the bench, as well as imposing term limits for currently life-tenured federal judges.

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O’Rourke floated the idea of having as many as 15 judges on the bench while speaking to supporters in Iowa earlier this month.

“What if there were five justices selected by Democrats, five justices selected by Republicans, and those ten then picked five more justices independent of those who chose the first ten?” he told supporters.

“I think that’s an idea we should explore.”

He added the idea of adding term limits on those justices so that there’s “a more regular rotation through there.” O’Rourke said the court should “be able to reflect the diversity” of America.

President Trump fired back at such proposals. "I wouldn’t entertain that. The only reason that they’re doing that is they want to try and catch up," he said when asked about so-called court-packing schemes.

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“The size of the Supreme Court is up to Congress and this is something that progressives have tried before, FDR famously tried to pack the court in 1937, his own party actually stopped him,” Yoo said on Fox & Friends.

“We’ve stayed at nine justices in the court for about 130, 140 years and it’s because it’s a simple number."