Sen.-elect John Fetterman's, D-Pa., incoming chief of staff vehemently pushed for Democrats to brand Supreme Court Justice Amy Coney Barrett’s nomination as "illegitimate" in order to pave the way for eventually eliminating the filibuster and packing more seats on the court.

Adam Jentleson – who previously worked in top roles for former Senate Majority Leader Harry Reid, D-Nev., and for multiple liberal organizations – penned an op-ed for the New York Times in September 2020, days after Ruth Bader Ginsburg’s death, arguing that while Democrats did not have the power to block a nomination by then-President Donald Trump, they could take certain measures to delay and delegitimize it.

"There are steps Democrats can take to apply maximum pressure, brand the process as the illegitimate farce it is and lay the groundwork for desperately needed reform that can reverse the damage early in 2021 if Democrats win in November," he wrote.

Those steps, Jentleson argued, included boycotting the confirmation hearings and "systematically denying" unanimous consent agreements, which would bring the business of the Senate to a halt.

John Fetterman won Pennsylvania's hotly contested U.S. Senate race on Nov. 8, beating Trump-backed Republican Mehmet Oz. (WHD Photo/Gene J. Puskar)

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"Together, these tactics will hang an asterisk around President Trump’s nominee," he wrote.

Jentleson said the process should motivate Democrats to commit to eliminating the filibuster if they regained power in the Senate, which they did several months later.

Sen.-elect John Fetterman speaks at a forum in Upper Darby, Pennsylvania, Nov. 4, 2022. (WHD Photo/Ryan Collerd)

"Without the filibuster, reforms can be passed by simple majority votes, as the framers intended. Democrats should commit to reforming the Supreme Court: They can add seats to the court; apply age or term limits; or pass any of a range of credible proposals," he wrote. "Democrats should also reform the Senate so it better represents the nation. They can start by inviting territories bound by federal law but lacking voting representation in Congress to become states. The District of Columbia has roughly a similar or greater population as Wyoming or North Dakota, while Puerto Rico has more people than 20 states. Both deserve to become states if they so choose."

Jentleson has repeatedly called for Democrats to expand the Supreme Court to ensure liberal rulings.

"There’s no downplaying the suffering [Coney Barrett] can cause from the bench. But to get her there, McConnell laid bare that this is all about power and Dems are poised to gain a lot of power a week from now. We have to vote," Jentleson tweeted on Oct. 26, 2020. "Then Dems have to use the power we give them to expand the court."

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"If you are not willing to reform the filibuster and expand the court, you are not willing to do what it takes to win this fight," he added in a Sept. 1, 2021 tweet. "If we keep playing beanbag while they play hardball, the results will be more of this. It's that simple."

Fetterman hired Jentleson, who has been advising the incoming senator during his transition, to be his chief of staff, Politico reported on Friday. Jentleson was most recently the executive director of the Battle Born Collective, a progressive consulting group he founded, and had also recently worked for left-wing groups Democracy Forward and Center for American Progress.

John Fetterman speaks to supporters at a "Get Out the Vote" rally in Pittsburgh, Pennsylvania. (Branden Eastwood/AFP via Getty Images)

Fetterman has previously said he does not support expanding the Supreme Court, and campaign spokesman Joe Calvello reiterated that to WHD News Digital on Sunday.

Responding to Jentleson's other comments, Calvello said Fetterman supports D.C. statehood and is for self-determination for Puerto Rico, and he "is open to studying other reforms to improve transparency and ethical standards of the Supreme Court and believes that President Biden’s Supreme Court commission was a good first step toward reaching a path forward."

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"John Fetterman is his own man with his own views; there is no one else like him in the U.S. Senate," Calvello said. "John is deeply proud of the team he is putting together for his Senate office and is keen on creating a team with diverse views and backgrounds so they can fully serve the people of Pennsylvania. This should not be hard to understand."

WHD News Digital's Thomas Catenacci contributed to this report.