Gun-control advocates hold a candlelight vigil outside the NRA headquarters in Fairfax, Va., on Monday. (Micahel A. McCoy/For The Washington Post)

Fresh calls for gun control following massacres in two U.S. cities over the weekend are testing the resilience of the National Rifle Association at a time when the nation’s largest gun lobby is riven by leadership clashes and allegations of reckless spending.

The NRA, which has blocked proposed restrictions after past mass shootings, including at Sandy Hook Elementary School in Newtown, Conn., has lost key veterans in recent months, including lobbyist Christopher Cox, who back-channeled with the White House and lawmakers during previous political crises. 

The NRA’s longtime advertising firm, which helped craft its hard-edge responses to past gun violence, is battling the organization in court. Last week, three NRA board members resigned, saying they were sidelined after demanding audits of the organization’s spending. Rank-and-file members are urging changes, while other gun-rights groups are seeking to capi­tal­ize on the NRA’s struggles.

The dissent surfaced on Tom Gresham’s syndicated radio show, “Gun Talk,” over the weekend after the back-to-back shootings in El Paso and Dayton, Ohio.

“Something’s gone wrong there,” a caller from Tulsa said Sunday afternoon. The NRA “will not get another dime of my money until we get an accounting.”

Emily McPhie from March for Our Lives holds a candle during a vigil outside NRA headquarters Monday to honor of the victims of two recent mass shootings. (Micahel A. McCoy/For The Washington Post)

That’s an increasingly common sentiment among listeners to Gresham, who has called for NRA chief executive Wayne LaPierre to resign.

“Everyone on the gun-rights side is concerned with what’s going on at the NRA because they recognize the vital role it plays in protecting our civil rights,” the radio host said in an interview. “We would like to get through this turmoil and get to the other side as quickly as possible so we can get back to the work of protecting the Constitution.”

NRA officials did not respond to requests to interview LaPierre. Marion Hammer, one of his most outspoken defenders on the 76-member board, said the group would not be distracted from its core mission.

“I don’t have a crystal ball and I never make predictions, but the one thing I can say for certain is that the NRA will fight to protect the Second Amendment as hard as we always do,” said Hammer, who lobbies for gun rights in Florida. “Protecting the Second Amendment comes first, and it always will.”

After the massacres in El Paso and Dayton that killed 31 people, former vice president Joe Biden and other Democratic presidential candidates renewed calls for an assault weapon ban and other measures to try to curb gun violence. Grieving residents of Dayton shouted, “Do something!” at Ohio Gov. Mike DeWine (R), who then on Tuesday proposed increasing background checks and other measures. Outside the NRA headquarters in Fairfax, Va., on Monday evening, gun-control activists held a vigil and demanded that lawmakers take action.

There have been 165 mass shootings in the United States. All but three were committed by men. Is it time for masculinity to enter the gun debate? (REF:demarcon,REF:oconnore,REF:hashemis/The Washington Post)

But there is little sign of momentum behind specific proposals in Washington that would test the NRA’s vaunted ability to mobilize its millions of members.

A handful of Republican lawmakers on Sunday endorsed stricter gun controls, but the GOP largely ignored Democratic demands that the Senate abandon its summer recess and return to Washington to address the issue. Senate Majority Leader Mitch McConnell (R-Ky.) has refused to consider restrictions the House passed in February, the first federal legislation of its kind since the late 1990s.

Although President Trump called for “strong background checks” on Twitter, in a national television address Monday he blamed “mental illness and hate” for the shootings. The only limits on gun sales he mentioned were “red-flag laws” that aim to identify mentally ill people who should not be allowed to buy firearms.

Focusing on mental illness, not restricting gun sales, has long been an NRA talking point in the aftermath of shootings. 

In one of two brief statements released since the weekend massacres, the organization said it “welcomes the President’s call to address the root causes of the horrific acts of violence that have occurred in our country. It has been the NRA’s long-standing position that those who have been adjudicated as a danger to themselves or others should not have access to firearms and should be admitted for treatment.”

Although Trump has mocked lawmakers as fearful of the NRA, he has repeatedly lavished praise on the organization, whose political arm spent $30 million to help elect him. The president has tweeted support for the NRA nearly a dozen times since early last year, most recently lamenting that “our great NRA” is a “victim of harassment” by the New York attorney general, which is investigating the tax-exempt group’s spending.

He has also expressed concern about the ongoing turmoil at the organization, tweeting in April, “It must get its act together quickly, stop the internal fighting, & get back to GREATNESS - FAST!”

Still, some gun-control advocates are seizing on the upheaval inside the NRA to argue that its sway on Capitol Hill is weakening. 

“The gun lobby is really crumbling; the NRA is imploding,” said Sen. Richard Blumenthal (D-Conn.), whose home state was where 20 children were killed at Sandy Hook Elementary School in 2012. “The vise lock grip of the whole gun lobby is breaking.” 

Blumenthal and Sen. Lindsey O. Graham (R-S.C.) are writing legislation that would offer federal grants and other incentives for states to pass legislation for emergency risk protection orders. Those statutes would allow family members, law enforcement officials and others to petition a judge to bar firearms from someone they believe is an imminent threat to themselves or others.

As the NRA’s chief lobbyist, Cox announced his support for courts issuing risk protection orders in March 2018, about one month after a massacre at Marjory Stoneman Douglas High School in Parkland, Fla. But the NRA has opposed such laws in several states on the grounds that they do not protect due process rights.

The organization declined to comment Monday on Blumenthal’s proposal until it reviews the legislation. 

Cox’s abrupt resignation — along with those of some of his top aides — has left a void, with some Republicans lawmakers uncertain whom to talk to at the NRA, said one senior GOP aide who spoke on the condition of anonymity to describe internal conversations. Cox was a “whisperer to a lot of Republicans,” the aide said.

Cox — who stepped down after being accused of conspiring with ousted board president Oliver North to overthrow LaPierre — also played a central role in developing the group’s strategy. In the aftermath of the Sandy Hook massacre, Cox advocated for the group to take a lower-key approach amid a wave of national outrage, although LaPierre ultimately overruled him. 

“The question is, under the current turmoil and crisis, when they speak, will it be different than statements in the past?” said NRA member and firearms trainer Robert Pincus, who is advocating an overhaul of the organization’s board. “Has the current crisis caused them to reevaluate their message?”

Gun-control activists, who have been gaining clout and outspent the NRA in the 2018 midterm election, said they welcomed signs that the group was faltering, but remained pragmatic about prospects for new legislation. 

“The more energy the NRA has to use to deal with their problems, the harder it is for them to project their energy outward,” said David Chipman, senior policy adviser at Giffords, a group founded by former congresswoman Gabrielle Giffords (D-Ariz.), who was shot in 2011. 

“But I don’t underestimate their existing power,” he said, adding, “The NRA has made long-term investments into the president and members of Congress, and until we have different representation, their extreme views will dominate the debate.”

Although the internal chaos at the NRA has soured some of its members, activists said they remain unified in their support for gun rights, particularly in the face of calls for restrictions by Democrats.

And other pro-gun groups — some more hard-line than the NRA — are trying to fill any potential void.

Alan Gottlieb, founder of the Second Amendment Foundation, said he has seen an uptick in support of more than 20 percent in recent months. The additional resources, he said, will allow the group to file more lawsuits on behalf of gun owners.

 “The single biggest concern that attendees at our annual conference next month want us to address is picking up the NRA’s slack and building a firewall,” Gottlieb said. 

Adam Kraut, a past runner-up for the NRA board who turned down a chance to replace one of the recently resigned board members, on Monday joined a different gun-rights group, the Firearms Policy Coalition, as its new director of legal strategy.

Unlike the NRA’s decision to wait until the Blumenthal-Graham legislation is introduced to take a position, the coalition came out Monday in opposition to the measure.

“Red flag firearm prohibition and confiscation laws are unconstitutional, unsound, and dangerous policies,” the group said Monday. “Tell the key DC leaders that they MUST OPPOSE any attempt to pass these unconstitutional laws.”

Gun Owners of America, which bills itself as “the only no-compromise gun lobby in Washington,” also opposes what spokesman Erich Pratt calls “dangerous red-flag laws, better known as gun confiscation orders.”

The group, which has published criticism of the NRA on its website, is promoting a discounted annual membership of $15. That’s significantly less than the NRA’s $45 fee, though the group is offering a discount to $30.

Seung Min Kim, Carol D. Leonnig and Mike DeBonis contributed to this report.