US gun industry groups are engaged in an intense attempt to persuade state and federal lawmakers that gun shops should be considered “essential” businesses during the coronavirus crisis, and therefore allowed to stay open.

The National Shooting Sports Foundation (NSSF), one of the largest US pro-gun ownership groups, told its members this week it had been in contact with the White House, Capitol Hill and the Department of Homeland Security (DHS), to advocate for “national critical infrastructure industry” status.

“We want you to know the [NSSF] is hard at work for you during this challenging time as the nation faces the Covid-19 pandemic,” the group said in a statement.

According to the Wall Street Journal, Lawrence Keane, NSSF senior vice-president for government and public affairs, said in a letter to the DHS the “critical infrastructure” designation should be extended to the whole gun industry, including dealers and shooting ranges.

“Food, water, shelter and adequate medical care are paramount for survival, but so too is the ability for an individual to defend his or herself, their family, as well as their home, business and property,” Keane reportedly wrote.

According to the NSSF, gun dealers have reported an unprecedented surge in firearm sales, with lines forming outside gun stores and background checks up 300% on 16 March compared with the same day last year.

In Florida, the Miami Herald reported, background checks were up nearly 500% on last Friday alone, with 13,192 checks recorded compared to 2,646 on the same date last year.

Florida’s Firearm Purchase Program, which conducts background checks, posted a message on its website which said the volume of requests was so high it was “currently unable to receive customer service phone calls”.

Across the US, a patchwork of orders and local ordinances allowing gun stores to remain open as “essential businesses” has emerged as the coronavirus crisis has developed.

In Illinois, Governor Jay Pritzker declared that “firearm and ammunition suppliers and retailers, for purposes of safety and security” were deemed “essential” and could thus stay open.

In Connecticut, Democratic senator and gun-control advocate Richard Blumenthal argued that closing gun stores would be broadly in line with other anti-coronavirus measures, including restrictions on travel and assembly.

“Plain and simple, there is no reason why gun stores should be given this exemption,” the senator tweeted.

But the stores stayed open and the National Rifle Association praised the state governor, Ned Lamont, its legislative wing saying in a statement it thanked him “for upholding the right of law-abiding citizens to defend themselves and their loved ones”.

In Pennsylvania, Governor Tom Wolf allowed gun shops to open on a limited basis, reversing an earlier order at the urging of several state supreme court justices.

“I am extremely pleased that Governor Wolf has acknowledged that he may not eviscerate citizens’ inviolate rights, regardless of any states of emergency that may exist,” said Joshua Prince of the Firearm Protection Coalition, a group that filed a lawsuit opposing the gun shop shutdown.

State justice David Wecht said the governor’s initial order to close gun shops amounted to “an absolute and indefinite prohibition upon the acquisition of firearms by the citizens of this commonwealth – a result in clear tension with the second amendment” of the US constitution as well as the constitution of Pennsylvania itself.

Wolf’s office did not announce the policy change: it was included on an updated list of businesses subject to an order to close because they are deemed “non-life-sustaining”.

In Albuquerque, New Mexico, efforts to update a city ordinance granting the mayor emergency powers were approved only after repeated assurances from Mayor Tim Keller that the city would not restrict firearms sales.

In other jurisdictions, including San Jose and Castro Valley, California, local authorities have ordered stores to close.

“Since we don’t live in the wild west, where people are dependent on guns for food, and we do have a well-functioning police department, it would be hard to articulate a basis for arguing that a gun shop would be an essential service,” Sam Liccardo, the San Jose mayor, told the Wall Street Journal.

The Los Angeles county sheriff’s department began closing gun shops on Tuesday, but dropped the effort less than 12 hours later. Sheriff Alex Villanueva told FOX 11 the county legal counsel had issued an opinion that under Governor Gavin Newsom’s statewide executive order, gun stores should be classified as essential.