Shame on Harry Reid for killing any prospect of an assault weapons ban. I understand why he did it, but that doesn't make it right.

In his State of the Union address, President Obama spoke with fiery eloquence about the cost of gun violence. "They deserve a vote," the president said of the victims, challenging Congress to take a stand on reasonable legislation to keep deadly weapons out of the hands of killers.

Reid disagrees. The Senate majority leader decided Tuesday to abandon a proposal by Sen. Dianne Feinstein, D-Calif., that would have banned the sale of some military-style firearms - weapons designed not for sport or self-defense, but for killing enemy soldiers. Reid said he was dropping the measure because it would surely fail.

"I'm not going to try to put something on the floor that won't succeed," Reid said. "I ... think the worst of all worlds would be to bring something to the floor and it dies there."

He's wrong. The worst way to respond to the massacre in Newtown, Conn., would be to let political self-interest stand in the way of meaningful action. The parents of those 20 slain children deserve a vote on the assault weapons ban. The families of the 30,000 Americans who will be killed by gunfire this year deserve a vote. Bringing the measure to the floor of both the Senate and the House is the least Congress can do.

We all know what's happening here. Senate Democrats face a tough battle next year to hold on to their slim majority. Going on record in support of legislation that the gun lobby so vehemently opposes could cost some vulnerable incumbents their seats - and potentially make Mitch McConnell, R-Ky., the majority leader.

Reid said he could muster barely 40 votes for Feinstein's weapons ban. Even if all 53 members of the Democratic caucus supported it, the measure would still fall short of the 60 votes needed to break an anticipated GOP filibuster. And in the event that the measure somehow made it out of the Senate, it would be dead on arrival in the House. So why should Senate Democrats go out on a limb?

The answer is that this is not a moment to do the expedient thing but instead to do the right thing.

It is true that prospects are brighter for other proposals on gun violence. The most important is expanding and toughening the current system of background checks for gun buyers. Despite the National Rifle Association's opposition, sentiment for universal background checks - covering not just dealers but also ostensibly "private" sales at gun shows - seems close to a consensus.

I don't mean to downplay the significance of background checks, which could save lives by keeping guns out of the wrong hands. But let's not fool ourselves: The biggest factor in gun violence is the gun.

Yes, mental health is a serious issue. Yes, the violence in movies and video games is shocking. But these other factors do not begin to explain why there is so much more gun violence in the United States than in other industrialized countries.

Surely there are disturbed young men in Britain who are watching violent movies or playing violent video games at this very moment - just like their American counterparts. Yet the U.S. death rate from gun violence is 40 times higher than the British rate. Why?

The biggest factor has to be that British law makes it hard to buy a gun and U.S. law makes it easy. Blame Congress for not imposing reasonable controls on instruments of death.

I'd love to hear Reid and his colleagues in the Senate explain their political arithmetic to the parents of Newtown.

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