WASHINGTON (NewsNation Now) — Senate Republican leader Mitch McConnell warned of a “scorched earth” landscape if Democrats use their new majority to end the Senate filibuster, the long-standing procedure that can block partisan legislation.

“Let me say this very clearly for all 99 of my colleagues: Nobody serving in this chamber can even begin — can even begin to imagine — what a completely scorched earth Senate would look like,” McConnell said Tuesday in a Senate speech.

Senate Democrats are talking privately about changing the decades-old rules for the filibuster, which allows a single senator to block a bill by objecting. In earlier eras, senators would seize the floor, speaking for hours about their objections. They also used it to stall civil rights legislation in the middle of the 20th century.

Supporters of the process say it protects the rights of the party not in power, but detractors argue it is being used to block popular bills.

McConnell said the partisan gridlock of the Trump and Obama eras would look like “child’s play” compared to what’s to come.

“The Senate would be more like a 100-car pileup. Nothing moving,” McConnell said.

The GOP leader’s remarks come as the Biden administration is taking a victory lap over the just-passed $1.9 trillion virus relief package. President Joe Biden clarified that he backed reforming, rather than scrapping the filibuster Tuesday.

“I don’t think that you have to eliminate the filibuster, you have to do it what it used to be when I first got to the Senate back in the old days,” Biden told ABC News. “You had to stand up and command the floor, you had to keep talking.”

Senate Democratic leader Chuck Schumer brushed off McConnell’s remarks as a “diversion” and said he hopes to work with Republicans on the upcoming bills, but said all options for filibuster changes are on the table.

It takes 51 votes to change the Senate rules and do away with the filibuster, and Democrats do not appear to have support from within their ranks to do so, even with Vice President Kamala Harris serving as the tiebreaker. At least two Democratic senators, Joe Manchin of West Virginia, and Kyrsten Sinema of Arizona, have signaled their objections, but there may be more.

The Senate will be put to the test in the weeks ahead. As senators start considering the House-passed bills, Democrats will be testing Republican willingness to participate in the legislative process by amending the bills toward eventual passage. If Republicans simply block the bills, Democrats could lean in more forcefully to try to change the rules.

McConnell warned Democrats not to take the next step, unveiling the actions he could take in retribution.

“This is an institution that requires unanimous consent to turn the lights on before noon, to proceed with a garden-variety floor speech, to dispense with the reading of a lengthy legislative text, to schedule committee business, to move even non-controversial nominees at anything besides a snail’s pace,” he said.

Changes to the filibuster have been underway for a decade.

Democrats did away with the filibuster rules to overcome Republican stonewalling of President Barack Obama’s executive branch nominations and some judicial nominees. Republicans then escalated the process by eliminating the filibuster for Supreme Court justices, smoothing confirmation of President Donald Trump’s three high court nominees.