The White House promised a comprehensive series of measures, including gun control legislation, on Monday to prevent a recurrence of mass shootings such as the "horrific" attack in Connecticut that left 20 children and six teachers dead.
The pledge came as the first cracks began to appear in the seemingly impregnable opposition to gun controls.
Less than 24 hours after Barack Obama signalled that gun control would be a second term priority during a powerful speech on Sunday evening at a vigil for the victims in Newtown, at least two Democratic senators strongly identified with gun rights shifted position in favour of reform.
The killings in Connecticut appear to be bringing about a change in mood that was not evident after shooting sprees over the last decade. They include Virginia Tech in 2007, the attack on congresswoman Gabrielle Giffords last year and the Aurora cinema shootings in July this year.
On Monday Obama met Vice President Joe Biden, Education Secretary Arne Duncan, Attorney General Eric Holder, and Health and Human Services Secretary Kathleen Sebelius to discuss proposals aimed at reducing gun violence.
Biden will be put in charge of the initiative, the Washington Post said quoting unnamed sources close to the government.
At the emotional vigil in Newtown, Obama appeared to abandon his reluctance to take on the gun lobby and delivered an impassioned speech in which he said change had to come.
He did not specify what change he had in mind, or even whether it would include new legislation on gun control.
The White House spokesman, Jay Carney, when asked what kind of measures the president had in mind, said: "It is a complex problem that will require a complex solution. No single piece of legislation, no single action will fully address the problem."