JUST DAYS after Senate Majority Leader Harry M. Reid (D-Nev.) pulled the plug on an assault-weapons ban in Congress, lawmakers in Maryland are also getting cold feet about mounting a frontal challenge to the gun lobby by prohibiting sales of some of the most lethal firearms.

We disagree with Mr. Reid’s move on moral grounds; as President Obama said, the victims of mass murders deserved a congressional vote on assault weapons. But at least the Senate leader was operating according to strategic logic: Lacking the numbers to overcome a likely Republican filibuster, he was reluctant to force a floor vote that could imperil the reelection prospects of several of his fellow Democrats.

By contrast, the Maryland lawmakers now wavering on banning military-style weapons include Democrats who are highly unlikely to face a serious challenge in a general election. In fact, a number of them represent districts in Montgomery County where large majorities of voters favor gun control. They should favor prohibiting the sale of assault weapons such as the popular AR-15 because it’s the right thing to do to promote public safety and it would reflect the interests of their constituents.

After all, a variant of the AR-15 was used by John Allen Muhammad and Lee Boyd Malvo when they stalked innocent victims during their killing spree in the Washington area in 2002. Seven of the pair’s 13 victims were shot in Maryland.

Nonetheless, the AR-15 is the most notorious of the weapons that several lawmakers in the House of Delegates say they may exempt from the ban on prohibited firearms in Gov. Martin O’Malley’s gun legislation, which passed the state Senate.

This is illogical. Advocates of the AR-15 portray it as a weapon popular with sportsmen and hunters. They argue that since it fires bullets singly, it’s not inherently more dangerous than a handgun.

The reality is that there is a reason various types of AR-15s, and other assault weapons, have been favored by mass murderers, including Adam Lanza, who killed 26 at Sandy Hook Elementary School in Newtown, Conn., last December. They are equipped with an array of military features designed to inflict maximum harm on multiple people in a short time span.

A pair of Montgomery County Democrats, Dels. Luiz R.S. Simmons and Kathleen M. Dumais, both members of the House Judiciary Committee, said they were inclined to exempt the AR-15 from the weapons ban. Both said they’d been swayed by the pleadings of gun advocates who have flooded the legislative halls in Annapolis in recent weeks.

But the reality is that the number of Marylanders with a legitimate need to own AR-15s is minuscule. By contrast, repeated, tragic and bloody experience in Maryland and elsewhere in the United States makes plain the overwhelming need for a comprehensive ban on assault weapons.