There’s no fight the National Rifle Association is more eager to wage than the one over who will claim Antonin Scalia’s seat on the United States Supreme Court.

The NRA’s concern over the fate of the empty seat explains why the gun group endorsed Donald Trump earlier than any presidential candidate in its history; why it spent a record $30 million to elect him and defeat Hillary Clinton; and why in late March it launched a $1 million television ad campaign targeting four Senate Democrats up for re-election in 2018, all of whom hail from states that Trump won by double-digit margins last year.

On Monday, the NRA released a fifth spot directed at Michael Bennet, a Colorado Democrat who had not yet said how he will vote. Shortly thereafter, Bennet announced that he will oppose efforts to filibuster Neil Gorsuch, Trump’s nominee, who is a Colorado native and currently sits on the 10th Circuit Court of Appeals there.

The NRA’s message to these Democrats is simple: Break with your party and vote for Neil Gorsuch, the conservative federal judge from Colorado who Trump nominated for the seat, or face our deep pockets in your next campaign.

On its official website, the NRA loudly announces to visitors that it will spare nothing and no one to ensure the nominee reaches the bench.

“President Trump has nominated Neil Gorsuch for the Supreme Court!” a pop-up message reads. “The NRA has been with this President from the beginning. He has made an excellent choice. We are going [to] do everything in our power to seem him confirmed.”

Republican leaders have promised to confirm Gorsuch by Friday. While confirmation is likely, it is not inevitable.

The NRA thinks it can apply pressure to what it sees as vulnerable Democrats because of its impressive track record of taking down moderate lawmakers from conservative states who defy its will. In 2014, for example, the organization spent roughly $5.5 million to defeat Senator Kay Hagan, a North Carolina incumbent Democrat who voted a year earlier to expand background checks for buying guns.

But the current showdown is taking place in a different world. For one, it’s a Supreme Court fight. The NRA has also come to exclusively put its muscle behind Republican candidates during elections, and most Democrats no longer see an upside to staying in its good favor.

The NRA gave three of the senators targeted in its ads — Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota, and Jon Tester of Montana — grades of A- or better in 2012, when they last ran for election. But the value of these grades was undermined when, for example, the NRA spent roughly $400,000 supporting Donnelly’s opponent, and nearly $90,000 supporting Heitkamp’s. When it comes to Senator Claire McCaskill of Missouri, the other Democrat singled out in the campaign, there wasn’t even the illusion of friendliness. She received an F that year, and the organization spent about $360,000 trying to defeat her. Since then, her state has only become more bullish on matters involving gun rights, enacting a “stand your ground” law and a statute that removes permit and training requirements to carry concealed handguns in public.

“I think they’ve been running ads against me as long as I can remember,” McCaskill told The Trace. “That’s like the sun coming up in the morning.”

To say it plainly: The NRA has done pretty well over the last year. At the state level, the gun organization has successfully worked to expand gun carrying rights in Tennessee, Mississippi, New Hampshire, Ohio, West Virginia, and Idaho. When it gambled big on Trump, it poured huge sums into many of the same closely contested battleground states that provided his margin of victory.

On February 1, the day after he picked Gorsuch, Trump held a meeting with conservative leaders in the Roosevelt Room to discuss the nominee. Wayne LaPierre, the NRA’s executive vice president, was photographed sitting next to Trump. The picture now greets visitors to the NRA’s website.

To the NRA, Gorsuch taking a seat on the Supreme Court may surpass all of its recent accomplishments. It’s been only nine years since the high court ruled, for the first time in American history, that the Second Amendment protects the right of individual citizens to keep guns in their homes. On a closely divided court — and in a deeply divided country — one vote really matters.

“I think they’ve been running ads against me as long as I can remember. That’s like the sun coming up in the morning.”

Claire McCaskill, Senator from Missouri

The coming week should determine whether Gorsuch is confirmed. Chuck Schumer, the Senate minority leader, has promised to vote against Gorsuch, and to block the judge from receiving an up-or-down vote on confirmation. Schumer has urged his fellow Democrats to do the same.

Republicans enjoy a slim 52–48 majority in the Senate. In order to reach the number of votes needed for confirmation, they need at least eight Democrats to join them. Last week, Senator Joe Manchin of West Virginia, and Senator Heitkamp said they will vote with the GOP. Over the weekend, Donnelly announced that he would, too. McCaskill and Tester have said they will not support Gorsuch.

There’s only so much Democrats can do to stop Gorsuch. If there isn’t enough support to reach the 60-vote threshold, Senator Mitch McConnell, the majority leader, may pursue the “nuclear option,” a radical maneuver that would change the upper chamber’s rules, requiring only a simply majority to confirm Gorsuch.

The NRA’s ads are intended to avert the threat of a filibuster and assure confirmation. But the group is almost certain to oppose the lawmakers it is targeting even if they do break rank and vote to confirm. Over the last three election cycles, the NRA has become a Republican-only organization, spending tens of millions of dollars to elect GOP candidates, and virtually nothing to help Democrats.

Former Senator Mark Pryor of Arkansas knows this reality far too well. Coming from a conservative, pro-gun state, he was part of an older breed of Democrat and found it necessary to maintain a decent working relationship with the NRA. He entered the Senate in 2003 with an F, and over the next six years climbed his way up to a C-. But by 2010, with the Tea Party on the rise, Southern states were being pulled rightward. In April 2013, less than a year away from his next election, he was one of four Democrats (not counting Senator Harry Reid, whose vote had to do with procedure) who sided with the NRA and voted against expanding background checks. He helped give the organization a victory and killed a piece of legislation that had wide support among Americans, who were still reeling from the mass shooting at Sandy Hook Elementary School in Connecticut a few months earlier.

Despite his vote, the next year, the NRA gave him a B- and spent almost $3 million supporting his Republican opponent, who won by 17 percentage points.

“There’s really no advantage in Democrats trying to work with the NRA because, come election time, the NRA is not going to help them,” Pryor said. “They’ll twist and spin and mangle the facts, whatever they need to do.”

The three Democratic senators who joined Pryor in siding with the NRA in the vote against expanded background checks included Heitkamp; Max Baucus of Montana, who announced he would not seek reelection shortly after the vote; and Mark Begich of Alaska, who received less than $600 in support from the organization in 2014, while the NRA, simultaneously, contributed $2,000 to his opponent. Begich lost the race.

“At the very most, the NRA might give a Democrat some token support that doesn’t move the needle at all,” Pryor said.

The battle over Gorsuch’s nomination involves many powerful actors, including other special interest groups. Still, if Democrats are able to successfully block Gorsuch’s appointment despite the NRA’s lobbying, it would count as a major defeat for the organization.

The ads in the NRA’s latest campaign all adhere to the same format, charging that each senator betrayed their constituents by either voting to put “anti-gun justices onto the Supreme Court” — a reference to Justices Sonia Sotomayor and Elena Kagan — or by “voting for Barack Obama’s gun control.” The ads end with a dramatic call to action: “Your freedom is on the line,” the narrator intones.

The campaign follows a letter written on March 17 to Senate Democratic leaders by the NRA’s top lobbyist, Chris Cox, reminding them that Gorsuch has the organization’s “strongest support” and that “the votes on his confirmation will be considered in future candidate evaluations and we will notify our members accordingly.”

The NRA is scoring the votes, something it began doing in 2009 at McConnell’s urging.

A year earlier, in District of Columbia v. Heller, the Supreme Court for the first time affirmed the individual right to gun ownership in America, and the NRA needed assurance that that ruling would be preserved.

At the time, Democrats had control of both chambers of Congress, and if Republicans were going to have a chance at blocking President Obama’s agenda, they needed to present a united front. McConnell used the NRA to shore up his caucus, and for the next eight years it routinely deprived Obama of major policy victories.

“The politicization of the nomination process was well underway before the NRA jumped in,” said Robert Spitzer, a political scientist at the State University of New York, Cortland, and one of the country’s foremost experts on gun policy. “But they threw a log on the fire.”

Two Democratic Senate aides who declined to speak on the record said that the NRA’s growing reputation as a part of the Republican establishment reduces its ability to influence Democrats, even in gun-friendly states.

“People know they’re going to oppose Democrats,” one aide said. “They’re tuning them out.”

Taken together, the ads and the letter are meant to serve as warnings to senators from red states, but Democrats, even those representing conservative constituents, face as much or more pressure to oppose Gorsuch. During the 2018 midterms, when turnout is typically low, senators like McCaskill, Tester, Donnelly, and Heitkamp need enthusiastic support from their base.

Speaking to reporters on Tuesday as he entered a party lunch near the Senate chamber, Tester insisted the NRA was not on his mind while he weighed his vote on Gorsuch.

“I really should be feeling [pressure], but I don’t,” he said.