WASHINGTON (AP) — Minority Republicans used a Senate filibuster to block a Democratic bill that would have launched a bipartisan probe of the Jan. 6 attack on the Capitol. It was the first time under President Joe Biden that the GOP used the tactic to derail major legislation.

Yet the Republican victory Friday may prod Democrats closer to curbing or eliminating a legislative maneuver that’s been the bane of Senate majorities since the Founding Fathers.

Here’s a look at the filibuster and the political storm over it.

WHAT’S A FILIBUSTER?

Unlike the House, the Senate places few constraints on lawmakers’ right to speak. Senators can also use the chamber’s rules to hinder or block votes. Collectively these procedural moves are called filibusters.

Senate records say the term began appearing in the mid-19th century. The word comes from a Dutch term for “freebooter” and the Spanish “filibusteros” that were used to describe pirates.

Filibusters were emblazoned in the public’s mind in part by the 1939 film, “Mr. Smith Goes to Washington,” in which Jimmy Stewart portrayed a senator who spoke on the chamber’s floor until exhaustion. In a real-life version of that, Sen. Strom Thurmond, R-S.C., stood continuously by his desk for 24 hours and 18 minutes speaking against the 1957 Civil Rights Act, the longest Senate speech by a single senator for which there are records of speaking length.

Those days are mostly gone. Senators usually tell Senate leaders or announce publicly that they will filibuster a bill, with no lengthy speeches required. The impact usually flows not from delaying Senate business but from the need to get a supermajority of votes to halt them.

HOW DO FILIBUSTERS END?

Records from the first Congress in 1789 show senators complaining about long speeches blocking legislation. Frustration grew and in 1917, the Senate voted to let senators end filibusters with a two-thirds majority vote.

In 1975, the Senate lowered that margin to the current three-fifths majority, which in the 100-member chamber means 60 votes are needed to end filibusters against nearly all types of legislation. Only simple majorities are required to end the delays against nominations, thanks to recent years’ rules changes.

WHAT’S THE PROBLEM?

Democrats emerged from the 2020 elections controlling the White House, Senate and House. They had pent-up pressure to enact an agenda that includes spending trillions to bolster the economy and battle the pandemic, expanding voting rights and helping millions of immigrants in the U.S. illegally become citizens.

But Democrats have a slender House majority and control the 50-50 Senate only because of the tie-breaking vote of Vice President Kamala Harris. That means that to overcome a filibuster, Democrats need support from at least 10 Republicans, a heavy lift in a time of intense partisanship.

That’s frustrated progressive senators and outside liberal groups. They’ve pressured Senate Majority Leader Chuck Schumer, D-N.Y., to eliminate filibusters, even as their use has increased by whichever party is in the minority.

According to Senate records dating back to World War I, the number of votes to end filibusters in any two-year Congress never reached 100 until the 2007-2008 sessions. It hit a high of 298 in the 2019-2020 Congress, mostly on then-President Donald Trump’s appointees that majority Republicans were pushing to confirmation.

In this year’s first five months as of this week, there were already 41 votes to end filibusters, mostly on Biden’s nominees.

WHAT CAN DEMOCRATS DO?

It would take a simple majority, 51 votes, for the Senate to eliminate or weaken filibusters. GOP support for retaining them is solid, with Senate Minority Leader Mitch McConnell, R-Ky., saying Democrats want to end them in a quest for “raw power.”

But with Democrats eager to enact their priorities before they lose their fragile majority, their support for discarding filibusters has grown. Biden, who’s influential despite having no vote on the matter, has said the tactic is “being abused in a gigantic way.”

Yet Democrats lack the votes to do that. Their two most conservative senators, Joe Manchin of West Virginia and Arizona’s Kyrsten Sinema, have opposed a change, arguing the country is better served when Congress can find bipartisan solutions to its problems.

WHAT IMPACT MIGHT THE JAN. 6 COMMISSION VOTE HAVE ON FILIBUSTERS?

Democrats consider creating a commission to examine the violent attack on the Capitol by Trump supporters one of many issues they’re pushing that the public supports. Others include House-passed measures easing voting access, expanding citizenship opportunities for immigrants and curbing gun rights.

So far, Schumer hasn’t forced Senate votes on many such bills. But advocates of eliminating filibusters hope Friday’s vote blocking creation of a Jan. 6 commission, a top Democratic priority, will build pressure on Schumer, Manchin and Sinema to eliminate the maneuver.

Manchin called the GOP’s derailment of the commission “unconscionable” in a statement that gave no indication that his support for retaining filibusters had changed.

Schumer hasn’t overtly tipped his hand on what he’ll do but has kept the door open. The Senate spent much of this week debating a bipartisan bill aimed at strengthening the U.S.’s ability to compete economically with China, which some saw as demonstrating that Democrats work with Republicans when they can.

“We hope to move forward with Republicans, but we’re not going to let them saying no stand in our way,” Schumer said this week.

Democrats used special budget procedures to push Biden’s COVID-19 relief package through the Senate with just a simple majority in March. They may try the same with Biden’s huge infrastructure proposal, though Senate rules limit the ability to use that route.