In his very first speech as Senate majority leader in January, Sen. John Thune (R-S.D.) said, “And one of my priorities as leader will be to ensure that the Senate stays the Senate. That means preserving the legislative filibuster — the Senate rule that today has perhaps the greatest impact in preserving the Founders’ vision of the Senate.” This was a wise and prudent way to maintain the institutional strength of the nation’s upper chamber.  

This week, however, that strong institutional commitment to the rules of the U.S. Senate may face a significant test.  

Republican leaders are considering whether to overrule the parliamentarian to pass legislation with a simple majority. They want to invoke the Congressional Review Act to permanently block California from imposing stringent regulations on gas-powered cars. This issue, deeply rooted in a long history of environmental and states’ rights debates, is a polarizing topic for both parties. But you don’t have to like California’s policy at all to recognize that throwing out the rules to tackle what many might view as a misguided move can have unforeseen consequences.  

Republicans believe they are positioned to resolve this issue decisively. However, their path forward would involve ignoring the Senate parliamentarian, who has ruled that the California waiver isn’t subject to the Congressional Review Act, in which case a simple majority vote would not be sufficient to pass it. Critics have rightly warned that taking this route could set a dangerous precedent, opening the door to more legislative decisions being made by a simple majority and undermining needed Senate norms. 

Thune, who now holds the power to pursue this strategy, has cautioned against such erosion of Senate rules. As he has stated, “There are a lot of people out there who would like to see the Senate turn into a copy of the House of Representatives. And that is not what our founders intended or what our country needs.”

As a former member of the House, I couldn’t agree more.  

Thune’s concerns are valid. Overruling the parliamentarian on one issue would likely lead to further challenges to the institution’s norms, with members justifying exceptions for their own legislative priorities. In the future, a Democratic majority could seize on such precedents, reshaping the Senate’s role entirely.

Over the last four years, the GOP celebrated the fact that independent Sens. Joe Manchin and Kyrsten Sinema didn’t join those who wanted to overthrow the norms of the institution and get rid of the filibuster. If they had done so when Democrats held the House, Senate and White House, policies that Republicans strongly opposed could have been enacted by a simple majority vote in the Senate. 

If Republicans go back on that position now, are they so certain of a permanent majority that they won’t rue the day this comes back to bite them? Democrats, no doubt, still regret Harry Reid’s abandonment of the judicial filibuster and the current makeup of the Supreme Court that his decision brought forth.  

Both parties have previously flirted with procedural maneuvers to advance their agendas. Democrats have sought to use similar methods to raise the minimum wage and tighten emissions standards. Republicans have tried to use it to dismantle the Affordable Care Act. The question is whether enough members will rise above the immediate pressures of today’s partisan debates to safeguard the Senate’s long-term role.  

Sen. Lisa Murkowski (R-Alaska) has expressed reservations. Others, including Republican Sens. Susan Collins (Maine) and John Curtis (Utah), have drawn a clear line. “A red line for me is removing the filibuster; another red line for me is overruling the parliamentarian,” Curtis said. Their embrace of institutional norms should be welcomed.  

Not long ago, even some of the current advocates for procedural changes stood firmly against altering Senate rules. In 2021, when Democrats considered similar tactics, Sen. John Barrasso (R-Wyo.) argued, “The Senate is supposed to cool things down. We’re supposed to think things through. We’re supposed to stop bad ideas and stop the House from moving too fast. Changing the rules of the Senate would make that impossible.” 

The Senate is at a crossroads. While the political gains from overruling the parliamentarian may seem appealing, the long-term costs to the institution’s credibility and functionality could be immeasurable. The Senate’s identity as a deliberative body hinges on its commitment to rules and traditions, even when they inconvenience the majority. The question now is whether today’s senators will heed this lesson, or if they will sacrifice the chamber’s legacy for the politics of the moment. 

Barbara Comstock, a Virginia Republican, was a member of the U.S. House of Representatives from 2015 to 2019.