Six Democratic presidential candidates say Walmart should stop selling guns In Iowa, Warren, Klobuchar and Harris all demand Walmart stop selling guns.

A week after two mass shootings in Texas and Ohio, a growing number of Democratic presidential candidates are calling on Walmart, one of country's leading sellers of firearms, to stop selling guns.

The calls came as candidates gathered on Saturday at the Iowa State Fair and a rally put on by the gun-control groups in Des Moines.

On Friday, four candidates -- Senators Elizabeth Warren of Massachusetts, Bernie Sanders of Vermont, Cory Booker of New Jersey, as well as Julian Castro, the former mayor of San Antonio -- took to Twitter to call on the retailer to change its policy after 22 people were shot dead a week earlier at a Walmart in El Paso.

Warren, who appeared to be the first candidate to publicly take the position, said that Walmart could follow the example of the CVS pharmacy when it voluntarily stopped selling tobacco products in 2014, a move Warren said had helped reduce cigarette sales nationally.

Walmart declined to comment about the calls, but referred a reporter to a tweet by Dan Bartlett, Walmart's executive vice president of corporate affairs saying that the retail giant would be "thoughtful and deliberate" in its response to the El Paso massacre.

"Walmart doesn’t sell handguns (except in Alaska) or military-style rifles. We’ve also increased purchase age & don’t make any sale without government-approved background check," the tweet said.

In 2015, Walmart said that it would no longer sell high-powered rifles, which were associated with multiple mass shootings, at its U.S. stores.

In the days since the shootings, which claimed a total of 31 lives and left many more injured, Democratic lawmakers have stepped up their call for universal background checks, an assault weapons ban and other measures that they say would reduce mass shootings.

As candidates mingled with potential voters at the Iowa State Fair on Saturday, they were pressed on whether they agreed with the position taken by rival candidates.

When pressed if Walmart should stop selling guns, Senator Kamala Harris of California said, “yeah I do...it’s not that everyone needs to stop selling guns, but there need to be checks and balances.”

Asked the same question later in the afternoon, Senator Kirsten Gillibrand of New York simply said, “Yes.”

Congressman Tim Ryan of Ohio suggested that the retailer might reconsider the types of firearms that it makes available, and pointed to the decision by Dick's Sporting Goods in the aftermath of the shooting at a school in Parkland, Florida, to stop selling assault weapons and to raise the minimum age to purchase a firearm to 21.

Of Walmart, he said: "I think if you keep it to hunting rifles and those kind of things. I think that's appropriate."

Edith Honan contributed to this report.