If Democrats ever eliminate the filibuster, would it change the Senate and inject chaos into the workings of the government? Last week, Senator Mitt Romney of Utah raised that prospect, saying that without the filibuster, “whenever one party replaced the other as majority, tax and spending priorities would change, safety net programs would change, national security policy could change.” This is a common argument against ditching the filibuster and its minimum 60-vote requirement to end debate on most legislation.

A Senate without the filibuster would be different — but majority parties would still sometimes have difficulty legislating, and its longer terms mean it would not immediately transform into the House. What’s more, the filibuster is itself already causing chaos: The tactics used by recent Congresses to get around it, especially under unified party control, can create exactly the kind of policy instability Mr. Romney warned about.

It’s true that some legislation held up by the filibuster would likely be approved if it were gone. The John Lewis voting rights act — which Senator Joe Manchin reportedly supports — might fall into that category.

We also have evidence that eliminating the filibuster can make a difference in the Senate’s output. After a procedural change that allowed a simple majority of senators to end debate on nominations of lower court judges in 2013, for example, the Senate processed President Barack Obama’s appointees to these positions more frequently and more quickly.

But other realities of the contemporary Congress indicate that eliminating the filibuster would not necessarily usher in periods of rapid, vacillating policy change. As the political scientists Jim Curry and Frances Lee have documented, in recent decades, the filibuster is sometimes to blame when congressional majorities have struggled to pass their agenda items during periods of one-party control. But more often, the cause of inaction has been divisions within the majority party itself.

In 2017, for example, despite majority control in Washington, Republicans could not fulfill their promise to repeal the Affordable Care Act, and it wasn’t the fault of the filibuster. The party was trying to eliminate the act through the budget reconciliation process — a process that allows the Senate to advance certain spending and tax bills on a simple majority vote — but failed because it lacked sufficient support from Republican senators.

The Senate’s rules aren’t magic. Shifting the threshold to a simple majority would not force agreement where agreement on the underlying policy simply does not exist, just as maintaining the filibuster does not miraculously bring the two parties together.

The prevalence of the filibuster has made the reconciliation process increasingly attractive, especially in periods of unified party control. But this tactic comes with costs as well as benefits. The Senate’s Byrd rule imposes constraints, including a limit on the long-term budgetary effects of legislation passed using the procedure, that invite policy instability. Reconciliation often forces bill drafters to make provisions temporary and, as we saw with negotiations among Democrats in 2021, to make explicit trade-offs between fewer priorities for longer periods or more achievements for smaller windows.

In some cases, programs initially adopted for the short term are made permanent, like many of the tax cuts enacted under the George W. Bush administration (though only after substantial uncertainty about their prospects). But in other cases, extension is by no means guaranteed. The child tax credit, for example, was expanded and converted into monthly payments as part of a reconciliation bill passed in March 2021 — but only on a temporary basis. For the millions of Americans who benefited from the policy, the increased payments phased out just months after they began.

The constraints created by the reconciliation process may not have been the only obstacle to longer-term policy for Democrats. But when reconciliation is the most appealing path for majorities to get around the filibuster, it gives parties an additional reason to legislate for the short term and hope that political support for making a policy permanent materializes in the future.

Another way current legislating in Congress creates policy uncertainty is by making it more difficult to revisit legislation, especially bills adopted via reconciliation. Revisions may be vulnerable to the filibuster. Take one of the Supreme Court challenges to the Affordable Care Act, King v. Burwell. The case hinged on a drafting error related to individuals’ eligibility for subsidized insurance coverage that might have been more easily corrected by Congress in the absence of the filibuster. Instead, the case created more than a year of uncertainty for Americans around whether the law would stand.

The degree to which policies should change when the party in power changes is a central tension in a representative democracy. The current reality, in which majorities struggle to follow through on their promises, often leaves voters, in the words of Mr. Curry and Ms. Lee, in a state of “constant disappointment.” History suggests the Senate is on a long march to rule by simple majority, but given intraparty divisions, that discontent might persist even in a postfilibuster world.

But the status quo — in which the very tools available to get around the filibuster encourage policy uncertainty — is no recipe for sustained, consistent policy, either.

Molly E. Reynolds (@mollyereynolds) is a senior fellow in governance studies at the Brookings Institution and the author of “Exceptions to the Rule: The Politics of Filibuster Limitations in the U.S. Senate.”