Walmart, the world's biggest retailer, announced on Tuesday that it will stop selling ammunition for assault-style rifles and handguns, one month after a gunman walked into an El Paso, Texas, Walmart with an AK-style semiautomatic rifle and killed 22 people.

Walmart said it will stop selling the ammunition after its current inventory for assault-style rifles and handguns is depleted. The company also will stop selling handguns in Alaska, the only state where it had continued to sell them after ending the sale of handguns in all stores more than two decades ago.

Walmart CEO Doug McMillon said Walmart's changes were prompted by the El Paso shooting, as well as recent mass shootings in Dayton, Ohio, and Midland and Odessa, Texas.

He said that he also will be sending letters to the White House and congressional leaders, asking for action on "common sense measures". McMillon said that Congress should debate reauthorizing an assault weapons ban and expand background checks.

"We encourage our nation's leaders to move forward and strengthen background checks and to remove weapons from those who have been determined to pose an imminent danger," he said. "Congress and the administration should act. Given our decades of experience selling firearms, we are also offering to serve as a resource in the national debate on responsible gun sales."

In Washington, Senate Majority Leader Mitch McConnell said on Tuesday before Walmart's announcement that he won't put a gun bill of any kind on the Senate floor for a vote unless President Donald Trump says he would sign it into law.

The Kentucky Republican said on a radio show that he expects to get an answer from the Trump administration within the next week on what, if anything, it's prepared to support.

"If the president is in favor of a number of things that he has discussed openly and publicly, and I know that if we pass it, it will become law, I'll put it on the floor," he said.

McConnell has blocked nearly every piece of legislation passed by the Democratic-led House, including gun measures that have bipartisan support on Capitol Hill.

The National Rifle Association, a gun rights advocacy group, responded to Walmart's announced changes by saying "lines at Walmart will soon be replaced by lines at other retailers who are more supportive of America's fundamental freedoms".

Walmart's announcement on Tuesday is expected to reduce its share of the nation's ammunition market to 6 percent, from 20 percent. Walmart said last month that it accounted for about 2 percent of the nation's firearm sales.

Several years ago, Walmart stopped selling the type of assault-style rifle that was used in the El Paso shooting, but McMillon said the retailer recognized the need to do more "to make the country safer".

Walmart also said it no longer will allow shoppers to carry firearms openly inside any of its 4,700 US stores. Shoppers with concealed-carry permits can continue to carry guns, the company said.

McMillon said the company has no plans to discontinue all gun sales, adding that it has a long history of serving hunters and that founder Sam Walton was an avid hunter. Walmart will continue to sell long-barrel deer rifles and shotguns and much of the ammunition for those guns.

"I'm a gun owner myself," McMillon said. "In a complex situation lacking a simple solution, we are trying to take constructive steps to reduce the risk that events like these will happen again," he said. "The status quo is unacceptable."

The Associated Press and Reuters contributed to this story.