The head of the National Rifle Association said on Sunday "there weren't enough good guys with guns" to confront the gunman who killed 12 people at the Washington navy yard on Monday. Wayne LaPierre, the NRA's executive vice president, called for more armed guards and better security at military bases.

LaPierre's comments, in an interview with NBC's Meet the Press, echoed his response nine months ago to the Newtown school shooting, in which Adam Lanza killed 20 young children and six adults. Following Newtown, LaPierre's response was to call for an armed guard in every school, saying: "The only thing that stops a bad guy with a gun is a good guy with a gun."

On Sunday, LaPierre criticised what he said was a flawed security system that meant the navy yard had been "largely left unprotected". He also called for active duty personnel on military bases to be armed.

"There weren't enough good guys with guns," he said. "When the good guys with guns got there it stopped."

Revulsion over the Newtown shooting sparked a national debate which led to political momentum on gun control legislation, but such efforts have since stalled. In April, the Senate failed to advance a bipartisan proposal to expand federal background checks on gun sales. This month, the recall of two state legislators in Colorado who supported strict gun control laws also sounded a warning to lawmakers over the issue.

While Monday's shooting has put gun control into the spotlight once more, much of the political response has focused on security vetting at military bases and on mental-health issues, after details emerged about the troubled background of Aaron Alexis, the computer technician and former navy reservist who police identified as the navy yard shooter.

Chuck Hagel, the defense secretary, said "something broke down" in the vetting procedures that allowed Alexis to enter the navy yard and kill 12 people, before he was killed by police. It has emerged that Alexis, a defence contractor who was vetted for clearance in 2007, had been arrested twice for gun offences, although never charged. In August, he told police he was hearing voices. USIS, one of the US's largest security providers and the same firm that vetted National Security Agency whistleblower Edward Snowden, carried out vetting procedures on Alexis.

A survey for Gallup that was carried out two days after the Washington shooting revealed that 48% of Americans blame the mental health system "a great deal" for mass shootings in the US, a figure unchanged from January 2011. It also found that fewer people (40%) now blame easy access to guns for mass shootings than two years ago (46%), making the mental health system the perceived top cause of mass shootings.

The Gallup poll also showed a drop in public support for gun control laws following the navy yard shooting as compared to the aftermath of Newtown. Just under half – 49% – of those surveyed last week said they believed the laws governing the sales of firearms should be made stricter, compared to 58% who thought so immediately after the elementary school shooting in December.

LaPierre accused politicians of exploiting the navy yard shooting and "trying to stir this towards firearms". He said outrage over firearms should be directed at an "unprotected" naval base and a "broken" mental health system.

Asked if he would be comfortable with someone who had been voluntarily committed being barred from owning a gun, LaPierre said: "I think if they adjudicate you like Virginia has done now, where if you're involuntarily committed or if the mental-health people say you're dangerous, you need to be in the system."

He said people like Alexis should be committed and added: "If they're committed, they're not at the navy yard".

LaPierre said the records of those adjudicated to be dangerous are not entered into the national instant-check system for gun buyers. "So the Aurora shooter in Colorado gets checked and is cleared, the Tucson shooter gets checked and gets cleared, Aaron Alexis goes through the federal and state check and gets cleared."

A candlelight vigil held after the DC navy yard shooting. Photograph: Greg Kahn/Getty Images

On Sunday, President Barack Obama will address a memorial service for the victims of the navy yard shooting. On Saturday night, at the annual dinner of the Congressional Black Caucus Foundation, in Washington, Obama spoke of the "unspeakable grief" caused by recent mass shootings and of the difficulty he has faced trying to strengthen gun control measures through the legislative process. He vowed to "get back up and go back at it".

"Just two days ago, in my hometown of Chicago, 13 people were shot during a pickup basketball game, including a three-year-old girl," said Obama. "Tomorrow night I'll be meeting and mourning with families in this city who now know the same unspeakable grief of families in Newtown, and Aurora, and Tucson, and Chicago, and New Orleans, and all across the country – people whose loved ones were torn from them without headlines sometimes, or public outcry."

Obama concluded: "As long as there are those who make it as easy as possible for dangerous people to get their hands on guns then we've got to work as hard as possible for the sake of our children."