Senate Minority Leader Mitch McConnell (R-Ky.) warned of a Senate "nightmare" if Democrats do away with the filibuster.
McConnell said if the filibuster was removed, there would be "immediate chaos, especially in this 50-50 Senate."
"Taking that plunge would not be some progressive dream. It would be a nightmare," he said. "I guarantee it."
The Kentucky Republican continued in saying that progress on key issues would be hampered by rules and various procedures.
"Destroying the filibuster would drain comity and consent from this body to a degree that would be unparalleled in living memory," he added. "The Constitution requires the Senate to have a quorum to do any business. Right now, a quorum is 51 and the vice president does not count to establish a quorum. The majority cannot even produce a quorum on their own, and one could be demanded by any senator at almost any time."
Evenly split committees, he said, would also need a quorum to carry out any Senate business.
"Technically, it takes collegiality and consent for the majority to keep acting as the majority at any time they do not physically ... have a majority," McConnell added. "Every Senate Democrat and the vice president could essentially just block out the next two years on their calendar. They'd have to be here all the time."
It came after Sens. Kyrsten Sinema (R-Ariz.) and Joe Manchin (D-W.Va.) pledged they would not vote to undo the filibuster.
If Democrats remove the filibuster, "it would be immediately and painfully clear to the Democratic majority that they had indeed just broken the Senate," McConnell remarked, adding, "It would hamstring the Biden presidency over a power grab which the president has spent decades warning against."
Some Democrats have said they would push to remove the Senate rule if they secured a majority in the upper chamber. Among them, Sen. Mazie Hirono of Hawaii said in an interview Tuesday that the issue "is not dead" after two Democrats came out and said they wouldn't remove the filibuster.