WASHINGTON — Where is the NRA?

The nation’s largest gun-rights organization — typically outspoken about its positions even after shooting deaths — has gone all but silent since last week’s rampage at a Newtown, Conn., elementary school that left 26 people dead, including 20 children.

Its Facebook page has disappeared. It has posted no tweets. It makes no mention of the shooting on its website. None of its leaders hit the media circuit Sunday to promote its support of the Second Amendment right to bear arms as the nation mourns the latest shooting victims and opens a new debate over gun restrictions. On Monday, the NRA offered no rebuttal as 300 anti-gun protesters marched to its Capitol Hill office.

After previous mass shootings — such as in Oregon and Wisconsin — the group was quick to both send its condolences and defend gun owners’ constitutional rights, popular among millions of Americans. There’s no indication that the National Rifle Association’s silence this time is a signal that a change in its ardent opposition to gun restrictions is imminent. Nor has there been any explanation for its absence from the debate thus far.

The NRA, which claims 4.3 million members and is based in Northern Virginia, did not return telephone messages Monday seeking comment.

Its deep-pocketed efforts to oppose gun control laws have proven resilient. Firearms are in a third or more of U.S. households and suspicion runs deep of an overbearing government whenever it proposes expanding federal authority. The argument of gun-rights advocates that firearm ownership is a bedrock freedom as well as a necessary option for self-defense has proved persuasive enough to dampen political enthusiasm for substantial change.

Seldom has the NRA gone so long after a fatal shooting without a public presence. It resumed tweeting just one day after a gunman killed two people and then himself at an Oregon shopping mall last Tuesday, and one day after six people were fatally shot at a Sikh temple in Wisconsin in August.

The Connecticut shootings occurred three days after the incident in Oregon.

“The NRA’s probably doing a good thing by laying low,” said Hogan Gidley, a Republican strategist and gun owner who was a top aide to Rick Santorum’s presidential bid. “Often after these tragedies, so many look to lay blame on someone, and the NRA is an easy whipping boy for this.”

Indeed, since the Connecticut shootings, the NRA has been taunted and criticized at length, vitriol that may have prompted the shuttering of its Facebook page just a day after the association boasted about reaching 1.7 million supporters on the social media network.

Twitter users have been relentless, protesting the organization with hashtags like NoWayNRA.

The NRA has not responded to them. Its last tweets, sent Friday, offered a chance to win an auto flashlight.

Offline, some 300 protesters gathered outside the NRA’s lobbying headquarters on Capitol Hill on Monday chanting, “Shame on the NRA” and waving signs declaring “Kill the 2nd Amendment, Not Children” and “Protect Children, Not Guns.”

“I had to be here,” said Gayle Fleming, 65, a real estate agent from Arlington, Va., saying she was attending her first anti-gun rally. “These were 20 babies. I will be at every rally, will sign every letter, call every congressman going forward.”

Retired attorney Kathleen Buffon of Chevy Chase, Md., reflected on earlier mass shootings, saying: “All of the other ones, they’ve been terrible. This is the last straw. These were children.”

“The NRA has had a stranglehold on Congress,” she added as she marched toward the NRA’s unmarked office. “It’s time to call them out.”

The group’s reach on Capitol Hill is wide as it wields its deep pockets to defeat lawmakers, many of them Democrats, who push for restrictions on gun ownership.

The NRA outspent its chief opponent by a 73-1 margin to lobby the outgoing Congress, according to the nonpartisan Sunlight Foundation, which tracks such spending. It spent more than 4,000 times its biggest opponents during the 2012 election.

In all, the group spent at least $24 million this election cycle — $16.8 million through its political action committee and nearly $7.5 million through its affiliated Institute for Legislative Action. Its chief foil, the Brady Campaign to Prevent Gun Violence, spent just $5,816.

On direct lobbying, the NRA also was mismatched. Through July 1, the NRA spent $4.4 million to lobby Congress to the Brady Campaign’s $60,000.