There’s a TV ad that’s been running in Louisiana:It’s evening and a mom is tucking in her baby. Getting a nice text from dad, who’s away on a trip. Then suddenly . dark shadow on a window. Somebody’s smashing the front door open! Next thing you know, there’s police tape around the house, blinking lights on emergency vehicles.

“It happens like that,” says a somber narrator. “The police can’t get there in time. How you defend yourself is up to you. It’s your choice. But Mary Landrieu voted to take away your gun rights. Vote like your safety depends on it. Defend your freedom. Defeat Mary Landrieu.”Guns are a big issue in some of the hottest elections around the country this year, but there hasn’t been much national discussion about it. Perhaps we’ve been too busy worrying whether terrorists are infecting themselves with Ebola and sneaking across the Mexican border.

But now, as usual, we’re returning to the issue because of a terrible school shooting.

The latest . a high school freshman boy with a gun in the school’s cafeteria . occurred in the state of Washington, which also happens to be ground zero for the election-year gun debate. At least that’s the way the movement against gun violence sees it. There’s a voter initiative on the ballot that would require background checks for gun sales at gun shows or online. “We need to be laser focused on getting this policy passed,” said Brian Malte of the Brady Campaign.

Think about this. It’s really remarkable. Two years after the Sandy Hook tragedy, the top gun-control priority in the United States is still background checks. There is nothing controversial about the idea that people who buy guns should be screened to make sure they don’t have a criminal record or serious mental illness. Americans favor it by huge majorities. Even gun owners support it. Yet we’re still struggling with it.

The problem, of course, is the National Rifle Association, which does not actually represent gun owners nearly as ferociously as it represents gun sellers. The background check bill is on the ballot under voter initiative because the Washington State Legislature was too frightened of the N.R.A. to take it up. This in a state that managed to pass a right-to-die law, approve gay marriage and legalize the sale of marijuana.

The N.R.A. has worked hard to cultivate its reputation for terrifying implacability. Let’s return for a minute to Senator Mary Landrieu, who’s in a very tough re-election race. Last year, in the wake of Sandy Hook, she voted for a watered-down background check bill. It failed to get the requisite 60 votes in the Senate, but the N.R.A. is not forgetting.

Nor is it a fan of compromise. Landrieu has tried to straddle the middle on gun issues; she voted last year for the N.R.A.’s own top priority, a bill to create an enormous loophole in concealed weapons laws. As a reward, she got a “D” rating and the murdered-mom ad. In Colorado, the embattled Senator Mark Udall, who has a similar voting record, is getting the same treatment.

The N.R.A.’s vision of the world is purposefully dark and utterly irrational. It’s been running a series of what it regards as positive ads, which are so grim they do suggest that it’s time to grab a rifle and head for the bunker. In one, a mournful-looking woman asks whether there’s still anything worth fighting for in “a world that demands we submit, succumb, and believe in nothing.” It is, she continues, a world full of “cowards who pretend they don’t notice the elderly man fall ...”Now when was the last time you saw people ignore an elderly man who falls down? I live in what is supposed to be a hard-hearted city, but when an old person trips and hits the ground, there is a veritable stampede to get him upright.

The ad running against people like Landrieu makes no sense whatsoever. If that background-check bill had become law, the doomed mother would still have been able to buy a gun for protection unless she happened to be a convicted felon. And while we have many, many, many things to worry about these days, the prospect of an armed stranger breaking through the front door and murdering the family is not high on the list. Unless the intruder was actually a former abusive spouse or boyfriend, in which case a background check would have been extremely helpful in keeping him unarmed.

A shooting like the one in Washington State is so shocking that it seems almost improper to suggest that people respond by passing an extremely mild gun control measure. But there is a kind of moral balance. While we may not be able to stop these tragedies from happening, we can stop thinking of ourselves as a country that lets them happen and then does nothing.

Unless your worldview is as bleak as the N.R.A.’s, you have to believe we’re better than that.