Faced with budget pressures and an invigorated gun control movement, the National Rifle Association has found a new cause amid the pandemic — fighting to keep gun stores open as its fund-raising appeals depict the government’s coronavirus response as a threat to Second Amendment rights.

On Thursday, the group sued the State of New York over its decision to include gun retailers among the many businesses that have been forced to close during the crisis. The N.R.A. had already filed two suits against California, where the governor had left the decision to counties.

The suits come as the N.R.A. and other gun groups have successfully lobbied the White House to get the Department of Homeland Security to add firearms vendors to its list of essential businesses. That prompted states like New Jersey to reverse course and allow such stores to remain open. But New York, the epicenter of the outbreak in the United States, has resisted, viewing the shutdown of businesses across the state as a vital safety measure.

“There isn’t a single person who has ever used a gun in self-defense who would consider it nonessential,” the N.R.A.’s chief executive, Wayne LaPierre, said in a statement, calling the shutdown of gun stores an assault “on our Second Amendment freedoms.”