EXPLAINER: What's the Senate filibuster and why change it?

Senate Republicans are poised to use a filibuster to derail Democrats’ effort to launch a bipartisan probe of the Jan. 6 attack on the Capitol. The showdown will be the first vote this year when the GOP has used the delaying tactic to try killing major legislation.

Yet while the GOP seemed certain to succeed Thursday, their victory may prod Democrats closer to curbing or eliminating a legislative tactic that’s been the bane of Senate majorities since the Founding Fathers.

Here's a look at the filibuster, how it works and the current political firestorm over it.

WHAT'S A FILIBUSTER?

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

Senate records say the term began appearing in debates 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. Today, senators usually tell Senate leaders or announce publicly that they will filibuster a bill, with no lengthy speeches required.

HOW DO FILIBUSTERS END?

Records from the very first Congress in 1789 show senators complaining about long speeches designed to block legislation. Frustration with the tactic grew and in 1917, the Senate voted to let senators end a filibuster 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 is 60 votes. That margin is needed to end filibusters against nearly all types of legislation, but no longer applies to nominations.

Democrats controlling the Senate in 2013, angered by GOP delays on then-President Barack Obama's picks, reduced the margin for ending filibusters against most appointees to a simple majority, exempting Supreme Court nominees. In 2017, Republicans in charge of the chamber, eager to add conservative justices under then-President Donald Trump, lowered the threshold to a simple majority for Supreme Court picks as well.

WHAT’S THE PROBLEM?

Democrats emerged from the 2020 elections controlling the White House, Senate and House. They took control with lots of 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, who have pressured Senate Majority Leader Chuck Schumer D-N.Y., to eliminate filibusters.

For Democrats, the problem is serious because the delaying tactic has become an increasingly common weapon for whichever party is in the minority.

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

In this year's first five months through Wednesday, there were already 41 votes to end filibusters, mostly on President Joe Biden s nominees.

WHAT CAN DEMOCRATS DO?

It takes a simple majority — 51 votes — to change how the Senate cuts off filibusters.

GOP support for retaining filibusters is solid, with Senate Minority Leader Mitch McConnell, R-Ky., saying Democrats want to end them in a quest for “raw power.”

As the threat of Republican filibusters has loomed this year, Democratic support for discarding filibusters has grown. That includes from Biden, who's influential despite having no vote on the matter and has said he's open to changing it because it's “being abused in a gigantic way."

Yet right now 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 that 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 just one of many issues for which they have majority public support.

Other bills in that category include House-passed measures easing state restrictions on voting procedures, expanding citizenship opportunities for immigrants and curbing gun rights bills.

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

Schumer hasn't overtly tipped his hand on what he'll do but has consistently kept the door open. It was noteworthy that 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 $1.9 trillion COVID-19 relief package through the Senate with just a simple majority in March. They may try the same with Biden's huge infrastructure bill, but Senate rules limit the ability to use that route.