The failure to win tougher background checks for gun purchases or other new firearms regulations are the "biggest frustration" of his term in office, President Obama said, as he decried school shootings that are "becoming the norm" in ways that "as a parent, are terrifying to me."
Answering questions on the social media site Tumblr, Obama said that gun violence in America is "off the charts" and that "we should be ashamed" of its prevalence.
He also brushed aside the argument made by some opponents of new gun regulations that mental illness, not guns, lies at the root of recent shootings.
"The United States does not have a monopoly on crazy people," Obama said. Yet "we're the only developed country" that suffers repeated mass shootings. "There's no place else like this."
Obama made his remarks after a period of just over two weeks in which the country has witnessed several high-profile mass shootings.
On May 23, a gunman killed himself and six others in Isla Vista, Calif., near UC Santa Barbara, four by shooting. On Sunday, two police officers, a third person and the two shooters were killed in Las Vegas. Shootings in recent days have taken the lives of students in Seattle and near Portland, Ore., and more than 30 shootings on school campuses have taken place this year, according to groups that track news reports.
Other leading Democrats have similarly raised the gun control issue in recent days.
"It's very few days go by that we don't have these killings," Senate Majority Leader Harry Reid of Nevada said Tuesday.
"The man in Las Vegas, clearly from what I've been able to read, was a felon. He couldn't have bought a gun if we had background checks," Reid said.
But Obama, whose effort to tighten gun regulations failed last year after the shootings in December 2012 in Newtown, Conn., held out little hope of change on the issue.
"If public opinion does not demand change in Congress, it will not change," he said, criticizing candidates and lawmakers who are "terrified of the NRA."
Although he has ordered some tightening of regulations using his executive authority, "we don't have enough tools right now to make as big a dent as we need to," he said.
"My biggest frustration so far is that this society has not been willing to take some basic steps" to curb gun violence, he said.