Breitbart News Chairman Stephen K. Bannon (Jonathan Ernst/Reuters)

Let's be clear about something: President Trump has not endorsed a ban on bump stocks — or any other new gun-control measure, in response to Sunday's mass shooting in Las Vegas.

But when counselor to the president Kellyanne Conway on Thursday dared to say on “Fox & Friends” that “we always welcome a thoughtful conversation on policy and issues,” the rebuke from Breitbart News came swiftly.

The mere thought of curtailing gun-ownership rights — in any way — is all it takes to arouse the anger of Breitbart, led by Trump's former chief strategist, Stephen K. Bannon.

No one can say the White House wasn't warned. Bannon told Axios on Tuesday that if Trump were to step left on gun control, it would be “the end of everything” and that, “as hard as it is to believe,” the reaction of the president's base would “actually [be] worse” than if he were to support a form of amnesty for undocumented immigrants.

Already, Breitbart is casting GOP lawmakers who say they would consider a ban on bump stocks as traitors to the Second Amendment.

“Cornyn cave?” read one headline on the hard-right website, referring to Sen. John Cornyn (R-Tex.), who said on Wednesday that a hearing on bump stocks would be “worthwhile.”

Analysis | Will Congress ban bump stocks, a gun accessory used in the Las Vegas attack?

A bump stock is a firearm attachment used by Las Vegas gunman Stephen Paddock that causes a semiautomatic rifle to slide back and forth, slightly but rapidly, in the hands of a shooter, thus depressing the trigger over and over — at a much faster rate than would be possible, otherwise. The device is legal because it does not, technically, convert a semiautomatic weapon, which reloads automatically but fires manually, into a fully automatic weapon, which continues to fire on its own after a single trigger pull.

Since a bump stock enables a gun that is semiautomatic to replicate the bullet stream of one that is fully automatic, however, some Republicans have suggested that perhaps the loophole that makes the attachment legal ought to be closed.

Breitbart called out Sen. Ron Johnson (R-Wis.), who said he would vote for a ban on bump stocks, and Sen. Jon Thune (R-S.D.), who said the Senate should “take a look at” such a prohibition.

“I think they should be banned,” Rep. Bill Flores (R-Tex.) told the Hill. “There's no reason for a typical gun owner to own anything that converts a semiautomatic to something that behaves like an automatic.”

This was Breitbart's take on Flores's remarks:

Sen. Dianne Feinstein (D-Calif.) introduced legislation to ban bump stocks on Wednesday. That means Flores and a leading Senate Democrat are in agreement on gun control, with both thinking more is needed in the form of a ban on ATF-approved bump stocks.

The good news for Republicans who get behind a ban on bump stocks is that they will have the cover of the National Rifle Association. In a statement issued on Thursday afternoon, the influential defender of gun rights said it “believes that devices designed to allow semiautomatic rifles to function like fully automatic rifles should be subject to additional regulations.”

It must be a relief for Republicans to know they will not face the fury of the NRA, if they support a bump-stock ban. But they will have to contend with the wrath of Breitbart, which dismisses the threat of bump stocks. Here's an excerpt from the site's coverage:

They are for novelty, and they work best for short bursts that mimic automatic fire at the gun range. Moreover, they render the gun less accurate.

But they are a blast for the common man who will never be able to afford a $15,000 to $50,000 machine gun. That man can work all week then take his AR-15 with a bump stock to the range on Saturday and enjoy himself as he mimics automatic fire for a few short bursts. That is why the bump stock was created. It has been cast in negative light only because the Vegas attacker used his bump stock criminally.

The question for Trump and other Republicans is whether they will be willing to cross Bannon and his media operation on gun control, even with the NRA behind them.