Delta Airlines is ending its discount contract with the National Rifle Association. Avis, Hertz, and Enterprise will stop offering NRA members discounts on rental cars. The First National Bank of Omaha will stop issuing NRA-branded credit cards.

These companies and more have pulled their support from the gun advocacy group in the wake of the school shooting in Parkland, Florida. If history is any guide, their moves could have a lasting effect.

Calls for companies to sever ties to the group began taking off on social media under the #BoycottNRA hashtag soon after the February 14 shooting, according to the Washington Post. Among the first to respond was First National Bank of Omaha, which announced on Thursday that “customer feedback has caused us to review our relationship with the NRA. As a result, First National Bank of Omaha will not renew its contract with the National Rifle Association.”

While the NRA has faced public pressure in the past, this the first time it’s been hit with such a broad boycott, according to Adam Winkler, a law professor at UCLA and the author of the book Gunfight: The Battle Over the Right to Bear Arms in America.

Something similar happened last year, when more than 80 brands pulled their ads from The O’Reilly Factor after sexual harassment complaints against host Bill O’Reilly became public. The advertising boycott wasn’t the only factor behind his ouster from Fox News, but it was a major one. Faced with an exodus of advertiser money, the network that had been protecting O’Reilly for years finally decided to cut ties.

As a nonprofit, the NRA isn’t beholden to advertisers the way Fox is. Still, O’Reilly’s trajectory is a reminder of how powerful boycotts can be. On the issue of gun control, where even repeated mass killings of children have failed to spur legislative action, the added pressure of corporate money might just be enough to produce change.

A boycott may have cost Bill O’Reilly his job

The boycott against O’Reilly came in April 2017, after the New York Times reported on decades of harassment allegations against the host. Fox had been aware of such allegations since 2004, when Andrea Mackris, a former producer on The O’Reilly Factor, filed a lawsuit accusing the host of telling her to buy a vibrator and describing sexual fantasies involving her, among other inappropriate behavior. In at least two cases, the network appears to have paid settlements to O’Reilly’s accusers of over a million dollars.

In other cases, Fox was aware of settlements paid by O’Reilly himself, including a $32 million agreement reached in 2016. Soon after that settlement deal was reached, Fox gave O’Reilly a four-year contract extension worth $25 million a year, according to the New York Times.

But in April 2017, brands like Mercedez-Benz, Jenny Craig, and Geico started pulling their ads from The O’Reilly Factor. Over the course of the month, the show lost about half of its national advertising buys.

At the time, public opinion of O’Reilly, even among viewers, was beginning to sour. Family dynamics among the Murdochs, who own Fox, may also have played a role in O’Reilly’s ouster. Still, the boycott provided a tangible, financial reason to get rid of O’Reilly, and it seems likely that it played a significant role in his eventual dismissal.

The NRA isn’t Fox News — but that doesn’t mean it’s not vulnerable

The NRA boycott is different from what happened to O’Reilly in a number of ways. Most obviously, the NRA, a nonprofit group, doesn’t depend on companies like Delta and Avis the way a TV show depends on advertisers. It does, however, depend at least to some degree on deep-pocketed donors — in 2016, the group’s political arm took in more than $124 million in contributions and grants from individuals, corporations, and other entities, including a single donation of $19.2 million, according to Mother Jones. An exodus of corporate partners could have a chilling effect on those donations.

That could affect the NRA’s influence on politics — in 2016, the group spent more than $54 million to help elect President Trump and other Republican candidates, Mother Jones reports. All but a few candidates who got support from the group won their elections. Fewer donations could mean less money to spend on future races.

The NRA also depends on corporations to help spread its message. NRATV, the group’s online video channel, has become a “vital forum for the dissemination of some of the most strident pro-gun messaging in politics today,” Jeremy W. Peters and Katie Benner reported at the New York Times.

Amazon, Apple, Google, and Roku are facing pressure to drop the channel from their streaming services in the wake of the Parkland shooting, according to USA Today. A Change.org petition asking Amazon to drop the channel had more than 170,000 signatures on Monday afternoon.

Roku appears to be sticking with the channel for now, according to USA Today, but Amazon, Apple, and Google have yet to weigh in. If they choose to end streaming for NRATV, the group will find it harder to get its message into American homes.

On the flip side, it’s possible the boycott could actually benefit the NRA in some ways, said Winkler. Criticism of the organization might produce a backlash, with gun enthusiasts deciding to contribute even more.

Gun rights advocates have already pledged on social media to boycott the companies cutting ties with the NRA, according to Business Insider. And the NRA has said the boycotts change nothing. “Let it be absolutely clear,” the group said in a statement. “The loss of a discount will neither scare nor distract one single NRA member from our mission to stand and defend the individual freedoms that have always made America the greatest nation in the world.”

Winkler doubts whether the NRA boycott will have much direct influence on legislators. However, he says, “the reason why these companies are boycotting the NRA is because they feel that consumers want them to boycott the NRA.” At election time, if consumers vote with the same passion they’re bringing to hashtags like #BoycottNRA, pro-gun lawmakers could be in trouble, and gun control legislation could have a better chance of passing.

“The reason why the boycott is happening is because there’s a real tide shifting in the gun debate,” added Winkler. He pointed to support among Florida Republicans for age restrictions on assault rifles, as well as the president’s promise to “take action” on guns. Elected officials aren’t responding to the boycotts, he said, but to the public opinion behind them.

Still, Winkler noted, corporate boycotts are “an increasingly important avenue for social change” in America. In addition to O’Reilly’s departure, the repeal of North Carolina’s anti-transgender “bathroom bill” may have been influenced by the NCAA’s pledge not to hold championship events in the state until the law was scrapped.

“One thing these cases show is that businesses exert a tremendous amount of political power and influence in America,” said Winkler, who has also written a book on the subject, We the Corporations: How American Businesses Won Their Civil Rights. “The good news is that is sometimes used for good causes. The bad news is that it’s almost always done to pursue profit.”

The line from boycott to gun control legislation in Congress is far from a straight one. But one thing is clear: in America, money talks. The NRA has long used this fact to its advantage. Now, it may be coming back to haunt them.