A year ago, on the day a gun control push in the Senate went down in flames, U.S. President Barack Obama stood with former Congresswoman Gabrielle Giffords and parents of Newtown shooting victims in the White House Rose Garden and declared, "This effort is not over."

On Tuesday, a mournful president conceded he was ashamed as an American and terrified as a parent that the United States can't find it in its soul to put a stop to rampant shooting sprees. Barring a fundamental shift in public opinion, Obama said, "it will not change."

"My biggest frustration so far is the fact that this society has not been willing to take some basic steps to keep guns out of the hands of people who can do just unbelievable damage," Obama said.

No developed nation on earth would put up with mass shootings that happen now once a week and disappear from the news within a day, Obama said — no nation except America.

It was a moment of bleak reflection and weary resignation for Obama, who thought universal background checks were the least the country could do after a 20-year-old with a semi-automatic rifle shot his way into a Connecticut elementary school in 2012 and massacred 20 children.

Most members of Congress — and to some degree this is bipartisan — are terrified of the NRA. — Barack Obama, U.S. President

"We should be ashamed of that," Obama said, hours after yet another deadly school shooting, this time in Oregon. "There's no place else like this."

The candid admission that gun control is all but a lost cause for his presidency marked a stark change in tone.

Despite shelving efforts to get Congress to vote on gun control, White House officials have always insisted they haven't abandoned the issue. In 2013, Obama issued 23 executive orders related to gun violence in an attempt to take whatever modest steps he could without requiring a congressional vote.

Obama said he respects gun rights and the American tradition embodied by the Second Amendment. But he blamed the National Rifle Association and well-financed gun manufacturers for making lawmakers "feel the heat" if they back tighter gun control.

"Most members of Congress — and to some degree this is bipartisan — are terrified of the NRA," Obama said, alluding to opposition from some Democrats that helped thwart the Senate effort.

He said the majority of Americans support gun control steps but don't feel passionately enough about it to punish lawmakers who disagree. "Until that happens, sadly, not that much is going to change."

'Why aren't we doing something about this?'

Just over half of Americans think U.S. gun laws ought to be stricter, an Associated Press-GfK poll in December found, while just 15 percent think they should be less strict. Other polls have found support for background checks on all gun buyers exceeds 80 percent.

Obama's public meditation on gun violence came as he took questions in the State Dining Room from young Americans through the social media site Tumblr. Although the session was focused on student loan debt, a student asked Obama about gun violence and said he had known one of the victims of last month's rampage in Isla Vista, California, that killed six.

The president recalled seeing the father of one of those victims appear on television, pleading with society not to let his son's death be in vain.

"As a father myself I just — I couldn't understand the pain he must be going through and just the primal scream that he gave out," Obama said. "Why? Why aren't we doing something about this?"