He did not describe the fight against the entrenched gun lobby, which wields substantial power in the US Congress, as an effort to confiscate weapons - a desire his most vehement conservative opponents often say he harbors.
But he suggested that the argument should be built more on the need to protect innocent, defenseless children.
"Can we say that we're truly doing enough to give all the children of this country the chance they deserve to live out their lives in happiness and with purpose?" he asked, as candles burned by his podium to remember the victims.
"I've been reflecting on this the last few days, and if we're honest with ourselves, the answer is no. We are not doing enough, and we will have to change."
Obama's impassioned remarks did not propose specific solutions, in keeping with the somber tone of the apolitical vigil service.
Heart-rending sobs broke the silence as Obama slowly read the names of the children whose lives were taken and the adults who died trying to protect them.
"They lost their lives in a school that could have been any school, in a quiet town full of good and decent people that could be any town in America," Obama said.
"We can't tolerate this anymore. These tragedies must end, and to end them we must change," the newly re-elected president said, implicitly rebuking those who argue that efforts to introduce more gun control laws would do little to stop killings.
Many states, including Connecticut, already have strict laws on the purchase of firearms, but with no federal statutes, there is little to stop the traffic of guns from other states where fewer restrictions apply.
Since the federal ban on assault weapons expired in 2004, efforts to revive it have failed.
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