Republican U.S. Sen. Pat Toomey denounced a plan backed by Democrats to kill the filibuster if their party sweeps the 2020 elections, accusing them of hoping to use the rule change to jam through an “extreme” left-wing agenda.

NBC News reports: “Veteran [Democratic] party operatives, activist groups and supportive senators are coordinating message and strategy to dial up the pressure to quickly end the 60-vote threshold early next year, fearing that preservation of the rule will enable Republicans to kill Joe Biden’s legislative agenda in its cradle.”

According to the report, these Democrats have hired “a war room” of research, communications and digital operatives with the mission of weakening support for the filibuster.

“In 2005, then-Senator Obama, in a speech in support of the filibuster, said its elimination would lead to more ‘bitterness and gridlock,’” Toomey told Delaware Valley Journal.

“Less than four years ago, Republicans had full control of the elected government and could have eliminated the filibuster, but we chose not to. Today, it seems ‘bitterness and gridlock’ is driving some Democrat politicians to flip-flop on the filibuster. Voters should be alarmed by efforts to quash minority voices in order to enact an extreme left-wing agenda.”

Although the delay tactic is generally coupled with legislation, it previously could be applied to a president’s nominations to the federal judiciary.

The filibuster is not a vote that kills legislation outright but rather a rule requiring three-fifths of the entire body — currently 60 senators of the 100 — to vote to end debate on legislation, allowing it to move forward. As a result, 40 senators can prevent legislation from getting a final up or down vote.

Eliminating the filibuster has long been called the “nuclear option” because, like nuclear war, it was viewed by both Republicans and Democrats in the Senate as an unthinkable act.

That changed in 2013 when then-Senate Majority Leader Harry Reid (D-Nev.) and the Democratic majority changed the rules to strip filibuster protections on votes to confirm Cabinet officials and judges, other than for the Supreme Court.

Since then, Republicans have removed the filibuster requirement from SCOTUS nominees in 2017 but drew the line at legislation. Now, it appears, Democrats are ready to erase that line, too.

Obama — like Toomey now — did warn against how divisive ending the filibuster would be.

“The American people want less partisanship in this town, but everyone in this chamber knows that if the majority chooses to end the filibuster — if they choose to change the rules and put an end to democratic debate — then the fighting and the bitterness and the gridlock will only get worse,” he said in 2005.

“If the right of free and open debate is taken away from the minority party, then the millions of Americans who ask us to be their voice, I fear that the already partisan atmosphere in Washington will be poisoned to the point where no one will be able to agree on anything,” the future president said.

However, President Obama reversed course and endorsed an end to the filibuster as he eulogized Georgia Democratic Rep. John Lewis this July, while calling for the passage of a voting rights act named in the congressman’s honor.

“If all this takes eliminating the filibuster, another Jim Crow relic, in order to secure the God-given rights of every American, then that’s what we should do,” Obama said.

Current Senate Minority Leader Chuck Schumer of New York told CNN in 2017 he regretted Democrats taking the “nuclear option” back in 2013.

However, as recently as the summer of 2019, Schumer told reporters that “nothing is off the table” if Democrats gain a Senate majority from the 2020 elections — something that would almost certainly make Schumer the Senate majority leader.

A request for comment to Pennsylvania Democrat Sen. Bob Casey’s office was not returned.