US President Barack Obama said in an interview broadcast Sunday that the massacre at a Connecticut elementary school which killed 20 young children was “the worst day of my presidency.”

Obama also expressed skepticism about a proposal by the gun lobby group The National Rifle Association to introduce armed guards in every US school and admitted there would be resistance to new proposals to control firearms.

“The question ... becomes whether we are actually shook up enough by what happened here that it does not just become another one of these routine episodes where it gets a lot of attention for a couple of weeks and then it drifts away,” Obama said.“It certainly won’t feel like that to me,” Obama said in an interview with NBC’s “Meet the Press.”

“This is something that was the worst day of my presidency. And it’s not something that I want to see repeated.”Obama has promised to unveil broad-based proposals to rein in gun violence in the United States in the New Year, but has also said he believes thereis a right in the US Constitution for individuals to bear arms.

He has committed to putting a halt to gun violence at the top of his agenda for his second term, though his remarks Sunday did not appear to signal an all-out effort to shape public opinion on the issue.On December 14, a disturbed man, 20-year-old Adam Lanza, killed his mother in their Newtown, Connecticut home before embarking on a horrific shooting spree at a local elementary school.

He blasted his way into Sandy Hook Elementary School and shot dead 20 six- and seven-year old children and six adults with a military-style assault rifle before taking his own life with a handgun as police closed in.The bloodshed, the latest in a string of mass shootings in the United States, reopened a national debate on the country’s gun laws, which are far more lax than in most other developed nations.

Obama also said the United States has some “very good leads” about who carried out the attacks in Benghazi, Libya, that killed four Americans including the US ambassador in September.He said that the United States would carry out all of the recommendations put forward in an independent review of the September 11 attack on the US mission in Benghazi in which Ambassador Christopher Stevens was killed.

“We’re not going to pretend that this was not a problem. This was a huge problem. And we’re going to implement every single recommendation that’s been put forward,” Obama said in the interview, referring to security issues identified in the review.With respect to who carried it out, that’s an ongoing investigation. The FBI has sent individuals to Libya repeatedly. We have some very good leads, but this is not something that I’m going to be at liberty to talk about right now,” he said.