Airlines United and Delta are the latest, and among the biggest, in a string of companies cutting largely promotional ties with the National Rifle Association in the wake of last week’s mass shooting at a Florida high school.

With announcements Saturday, they UAL, -3.61% DAL, -3.29% join a major bank, insurer and car-rental giant, among others, in announcing they were dropping partnership programs with the NRA.

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The NRA has been on the defensive amid renewed calls by a significant slice of the electorate to overhaul the nation’s gun laws to some degree while other Americans dig in on the basis of constitutional preservation. On Thursday, NRA Chief Executive Wayne LaPierre said those pushing to restrict gun sales “hate the Second Amendment, they hate individual freedom.”

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The website ThinkProgress last week named 22 major companies involved in corporate partnerships with the NRA, some of whom have since severed ties. Some activists have redoubled a call for consumer boycotts of companies that do business with the NRA. Their response is fueled in part by outspoken students angered by yet another mass shooting at a high school, the Valentine’s Day murders in Parkland, Fla. #BoycottNRA was trending on Twitter.

Amazon AMZN, -1.78% is also the target of a Twitter campaign urging consumers to rethink purchases on the e-commerce giant to reflect disapproval of its hosting NRA TV.

First National Bank of Omaha, the nation’s largest privately owned bank, said Thursday it will not renew its contract with the NRA for a branded Visa card.

“Customer feedback has caused us to review our relationship with the NRA,” a bank spokesman said in a statement. “As a result, First National Bank of Omaha will not renew its contract with the National Rifle Association to issue the NRA Visa Card.”

The bank had a relationship with the NRA for more than a decade, and the card touted a $40 cash-back bonus, enough to reimburse a one-year NRA membership.

Experts said severing such business ties is not without risk.

“This is a bold move for First National of Omaha but also a risky one because passions burn so hot on both sides of the topic of guns,” said Matt Schulz, senior industry analyst at CreditCards.com in an email.

“Many will applaud the move, but NRA members are famously loyal and the organization has shown itself as being very good at mobilizing its members, so there’s a real possibility of a significant backlash,” he said. “However, banks are in the business of managing risk of all kinds, and First National clearly sees this as one they’re willing to take in the wake of the tragic school shooting in Florida.”

On Thursday, privately held Enterprise Holdings Inc. — the parent company of the Enterprise, Alamo and National car rental brands — said it will end its partnership with the NRA, which gave NRA members discounts. In tweets, Enterprise Holdings said that program will end next month.

When asked for comment, a spokesperson for Enterprise Holdings said “We ended the discount program, effective March 26.”

Insurer MetLife MET, +0.89% also announced on Friday that it was ending its discount program with the NRA, adding, “we value all our customers.”

Avis Budget Group Inc. CAR, -5.00% , another company on the list, will no longer provide an NRA member discount starting March 26, according to a spokesperson.

Two others — security, storage and systems management solutions company Symantec Corp. US:SYMC and the privately-held alarm system company SimpliSafe — told MarketWatch on Friday that they have ended their relationship with the NRA. Symantec previously offered NRA members discounts, and SimpliSafe offered NRA members two months of home security system monitoring for free, according to ThinkProgress.

The telehealth platform Teladoc Inc. TDOC, +3.08% , which is also on the list, told MarketWatch that there was no direct Teladoc relationship with the NRA.

Information on the NRA’s site was part of a “broader program” set up by a third party a few years ago and is no longer active, a spokesperson said.

(Others so far, reportedly include Hertz Global Holdings Inc. HTZ, -2.94% and eHealth Inc. EHTH, +0.97% . They had not yet returned MarketWatch’s request for comment.)

Insurer Chubb Ltd. CB, +0.33% said it is ending participation in the NRA’s gun-owner insurance program, but it provided notice three months ago, according to the Associated Press. The program that provided coverage for people involved in gun-related incidents or accidents had been under scrutiny by regulators over marketing issues.

Other companies, including Wyndham Hotels US:WYN and Best Western hotels, have let social media users know they are no longer affiliated with the NRA, but they did not make clear when the partnerships ended.