The influence of the National Rifle Association, the nation’s highest-profile Second Amendment-rights organization and a longtime powerhouse against gun-control laws, is showing signs of potential decline.

The NRA’s own tax forms show a dip in revenue. And even as the group, now under the leadership of new president Oliver North of Iran-Contra fame, continues to spend big money on federal lobbying and political campaigns, its opponents in the gun-control movement, after decades of ever more deadly mass shootings and seemingly random incidents of gun violence, have been on the rise.

During the 2018 midterm elections, for example, gun-rights groups spent some $9.9 million on outside political efforts, nearly all of that from the NRA, while gun-control groups invested a record high of $11.9 million, according to a tabulation from the nonpartisan Center for Responsive Politics.

Andrew Arulanandam, a spokesman for the NRA, calls the decline in revenue between 2016 and 2017 temporary.

“Right now, we are at the highest levels of membership,” he said, with 5.5 million dues-paying members, the most in its 150-year history. “More people identify with the NRA and believe in what the NRA stands for than ever before.”

The NRA has found itself ensnared in controversy in recent months, some of it stemming from the special counsel probe into foreign interference in the 2016 elections. The group had ties to Maria Butina, a Russian who pleaded guilty late last year to charges of conspiracy to act as a foreign agent. Whether the gun group has allowed foreign money to infiltrate its campaign coffers also may be under investigation, according to news reports. And it’s on the hot seat for possible campaign finance violations of improperly coordinating its independent campaign expenditures with candidates, after a report by the liberal magazine Mother Jones.

On the policy front, the situation isn’t much better.

Even though the NRA’s favored candidates, including Donald Trump, won big in the 2016 elections, the group didn’t have any landmark successes in the 115th Congress and still will be pushing some of its key legislative priorities in the 116th Congress, including a bill from Texas Republican Sen. John Cornyn that would allow people with concealed carry permits from one state to use them in other states.

“The current patchwork of state and local gun laws is confusing and can cause the most conscientious gun owner to unknowingly run afoul of the law when they are traveling or temporarily living away from home,” said Chris W. Cox, executive director of the NRA’s Institute for Legislative Action, in a statement. The NRA’s news release said state gun laws “would still be respected.”

But such a measure is unlikely to get traction in the House. With Democrats now in control, the NRA will be on defense in the chamber, although any new gun-control measures passed there are unlikely to move in the Senate.

Meanwhile, even some historically pro-gun-rights states, such as Florida, have recently approved new measures aimed at curbing gun violence.

On Capitol Hill, House Democrats, many of whom ran in support of new gun-control and gun-safety measures, already have introduced a bill that would expand federal background checks to all gun sales.

But the NRA is expected to fight that.

“So-called universal background checks will never be universal because criminals do not comply with the law,” said NRA spokeswoman Jennifer Baker in a statement. “Instead of looking for effective solutions that will deal with the root cause of violent crime and save lives, anti-gun politicians would rather score political points and push ineffective legislation that doesn’t stop criminals from committing crimes.”

Although Democrats aren’t going to be able to get their own laws adopted, “the NRA will be stymied in watering down federal gun laws,” said Adam Winkler, a professor at the UCLA School of Law who specializes in the Second Amendment and gun control as well as a campaign finance law.

“It’s surprising that they’re stumbling just two years after an incredible amount of glory for them — the election of Donald Trump and an all-Republican Congress seemed like a boon to them,” Winkler added.

The Trump administration nevertheless issued a final rule in December prohibiting so-called bump stocks, which make semiautomatic rifles operate like a machine gun. The gunman who killed 59 people in a mass shooting in Las Vegas in 2017 used such a device. The NRA said it was “disappointed” that the administration didn’t offer amnesty for people who already owned bump stocks.

Winkler noted, however, that Trump’s presidency has resulted in two new Supreme Court justices, Neil M. Gorsuch and Brett M. Kavanaugh, who are widely viewed as champions of the Second Amendment, which gives Americans the right to keep and bear arms.

“The truth is, the NRA is still extremely powerful especially in the Republican Party,” Winkler said. “While Democrats did win the House, the Republicans that were elected tended to be very conservative and very pro-NRA.”

What’s new is that the NRA, besides taking a hostile tone with the political left and with the mainstream media, has expanded its messaging beyond just arms, including to the debate over immigration and border protection.

“The NRA is increasingly becoming a cultural warrior and not just on gun control,” Winkler said.

With Congress at a stalemate on gun-control efforts, states have moved ahead to enact their own new regulations. Florida, home of the February 2018 massacre at a Parkland high school, has put in place new age restrictions, requiring people purchasing a rifle to be 21, not 18, against the NRA’s objections.

Kris Brown, president of the Brady Campaign to Prevent Gun Violence, said the NRA has experienced a decrease in membership renewal rates but that the reason isn’t entirely clear.

“By their own admission, they are experiencing financial duress,” she said, citing legal documents the group filed as part of a court case involving the insurance company Chubb, which decided in early 2018 to no longer provide insurance through an NRA program offering coverage for gun owners for gun-related incidents.

The issue of gun control has risen to the top of some voters’ agendas, Brown noted.

The NRA still has its loyal base of Second Amendment supporters, but the growing list of deadly mass shootings has galvanized voters who disagree with the gun lobby’s point of view. Amid the devastation to families who have lost loved ones to mass shootings, a growing number of gun-control activists have become a political force.

“Now what we’re finding is it’s not just moms or grandmothers, it’s dads, it’s kids, it’s people of every stripe who are walking around saying, ‘I don’t feel safe at movie theaters, at school, synagogue and church,’” Brown said.

Many Americans have found the NRA’s resistance to seemingly modest gun-control measures, such as expanded background checks, an inadequate response to mass shootings, Brown added.

Nor is the group letting up on its adversarial and sometimes snarky tone. The NRA got into a public spat with doctors late last year.

“Someone should tell self-important anti-gun doctors to stay in their lane,” said a tweet from the NRA’s account. “Half of the articles in Annals of Internal Medicine are pushing for gun control.”

That tweet prompted a backlash from emergency room doctors, who began sharing their stories of treating gunshot victims.

“They do seem to be doubling down in their rhetoric,” Brown said. “At least based on their financials, it doesn’t seem to be working.”

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