WASHINGTON -- President Barack Obama reiterated his support Sunday for new gun control laws, vowing to mobilize public opinion in favor of substantive changes.

"I think anybody who was up in Newtown, who talked to the parents, who talked to the families understands that something fundamental in America has to change," Obama told David Gregory on NBC's "Meet the Press." "And all of us have to do some soul searching, including me as president, that we allow a situation in which 20 precious small children are getting gunned down in a classroom.

The challenge, he said, was turning that sadness into action.

"[T]he question then 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," the president said of the Dec. 14 shooting at Sandy Hook Elementary School in Newtown, Conn. "It certainly won't feel like that to me. This is something that -- ya know, that was the worst day of my presidency. And it's not something that I want to see repeated."

Obama laid out his support for three gun control provisions -- a ban on assault rifles, a ban on high-capacity magazines and a requirement for background checks at gun shows. He said he hoped to see something passed within a year, despite pushback from the National Rifle Association and similar groups.

"My response is something has to work," the president said. "And it is not enough for us to say, 'This is too hard, so we're not going to try.' So what I intend to do is I will call all the stakeholders together. I will meet with Republicans. I will meet with Democrats. I will talk to anybody."

But the president largely dismissed the NRA's suggestion of stationing armed guards at every school. "I am not going to prejudge the recommendations that are given to me," he said. "I am skeptical that the only answer is putting more guns in schools, and I think the vast majority of the American people are skeptical that that somehow is going to solve our problem. And, look, here's the bottom line. We're not going to get this done unless the American people decide it's important."

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  • Barack Obama

    President Barack Obama arrives at the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    President Barack Obama greets Gov. Dannel Malloy during his arrival at the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/The Hartford Courant, Stephen Dunn, Pool)

  • Barack Obama

    President Barack Obama pauses during a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • Barack Obama

    President Barack Obama walks off after delivering a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    President Barack Obama speaks during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • Barack Obama

    President Barack Obama greets State Senate Minority Leader John McKinney, R-Fairfield, on his arrival, before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting inside the Newtown High School auditorium in Newtown, Conn., Sunday night, Dec. 16, 2012. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/The Hartford Courant, Stephen Dunn, Pool)

  • Barack Obama

    President Barack Obama pauses as he delivers a speech during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    President Barack Obama speaks during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/The Hartford Courant, Stephen Dunn, Pool)

  • Barack Obama

    President Barack Obama pauses as he delivers a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    Residents pray during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • Barack Obama

    President Barack Obama pauses as he delivers a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • Barack Obama

    President Barack Obama pauses as he delivers a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • US-SCHOOL-SHOOTING-MEMORIAL

    US President Barack Obama makes his way off the stage after speaking at a memorial service for the victims and relatives of the Sandy Hook Elementary School shooting on December 16, 2012 at the Newtown High SChool in Newtown, Connecticut. Twenty-six people were killed when a gunman entered Sandy Hook Elementary and began a shooting spree. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • Barack Obama

    President Barack Obama walks off stage after delivering a speech at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    President Barack Obama pauses as he delivers a speech during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • US-SCHOOL-SHOOTING-MEMORIAL

    US President Barack Obama pauses as he speaks during a memorial service for the victims and relatives of the Sandy Hook Elementary School shooting on December 16, 2012 in Newtown, Connecticut. Twenty-six people were killed when a gunman entered Sandy Hook Elementary and began a shooting spree. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • Barack Obama

    President Barack Obama returns to the White House in Washington after attending an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jacquelyn Martin)

  • Barack Obama

    Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    Air Force One carrying President Barack Obama is seen leaving Bradley Air National Guard Base in East Granby, Conn., Sunday, Dec. 16, 2012. The president was in Connecticut to attend a memorial for the victims of the Sandy Hook Elementary School shooting where 26 people, including 20 children, were killed Friday. (AP Photo/Jessica Hill)

  • Julie LaPak, right, and Scott Emslie, of Newton, Conn., watch President Obama delver his speech at the Iron Bridge restaurant, Sunday, Dec. 16, 2012 in Newtown, Conn. (AP Photo/Mary Altaffer)

  • A mourner looks on during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Surendra Khera, left, Manjaree Daw, center and Indira Khera, of Simsbury, Conn., watch President Obama deliver his speech at the Iron Bridge restaurant, Sunday, Dec. 16, 2012 in Newtown, Conn. The president spoke during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Mary Altaffer)

  • Barack Obama

    Residents look on as President Barack Obama delivers remarks at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • A mourner weeps while listening to President Barack Obama speak on a loudspeaker while sitting outside a memorial at Newtown High School for the victims of the Sandy Hook Elementary School shooting, Sunday, Dec. 16, 2012, in Newtown, Conn. (AP Photo/David Goldman)

  • C.J. Singh, center, and other members of the Sikh community hold a candlelight vigil outside Newtown High School before an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Residents hold a candlelight vigil outside Newtown High School after President Barack Obama delivered remarks at an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • A young boy places a candle with others at the base of a flagpole outside Newtown High School before an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Eknoor Kaur, 3, stands with her father Guramril Singh during a candlelight vigil outside Newtown High School before an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Members of the Sikh community hold a candlelight vigil outside Newtown High School before an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • U.S. Sen. Joseph Lieberman, I-Conn., top right, Rep. Rosa DeLauro, D-Conn., left, Sen-elect Chris Murphy, center, and Lt. Gov. Nancy Wyman, right, wait for the arrival of President Barack Obama before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting inside the Newtown High School auditorium in Newtown, Conn., Sunday night, Dec. 16, 2012. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/The Hartford Courant, Stephen Dunn, Pool)

  • Residents look on during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. President Barack Obama is schedule to speak during the vigil. (AP Photo/ Evan Vucci)

  • Barack Obama

    Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. President Barack Obama is scheduled to speak during the vigil. (AP Photo/ Evan Vucci)

  • Barack Obama

    Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the school Friday and opened fire, killing 26 people, including 20 children. President Barack Obama is to scheduled to speak at the event. (AP Photo/ Evan Vucci)

  • Residents look on during an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. President Barack Obama is scheduled to speak during the vigil. (AP Photo/Evan Vucci)

  • Barack Obama

    Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • People wait in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Barack Obama

    Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • People arrive at Newtown High School to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Residents greet each other before the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Kayla Hopson and her daughter Lilliana, 9, left, and Janine Caswell and her daughter Genesis, 8, stand wrapped in Red Cross blankets to protect themselves from the cold, rainy weather as they wait in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Residents wait for the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Eight-year old Shayne Frate, a third grade student at Sandy Hook Elementary School, hangs from her mother Valerie's back, wrapped in a Red Cross blanket to protect her from the cold, rainy weather, as she waits in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • People wait in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Residents wait for the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Red Cross volunteer Michael Cianciolo distributes blankets to protect people from the cold, rainy weather as they wait in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Red Cross personnel provide blankets, water, snacks and even stuffed toys to keep people comfortable as they wait in line to attend an interfaith vigil with President Barack Obama, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Jason DeCrow)

  • Residents wait for the start of an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/Evan Vucci)

  • Barack Obama

    Residents greet each other before an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012 at Newtown High School in Newtown, Conn. A gunman walked into Sandy Hook Elementary School Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • Barack Obama

    Residents greet each other before an interfaith vigil for the victims of the Sandy Hook Elementary School shooting on Sunday, Dec. 16, 2012, at Newtown High School in Newtown, Conn. A gunman walked into the elementary school Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)

  • A U.S. flag flies at half staff outside the Newtown High School before President Barack Obama is scheduled to attend a memorial for the victims of the Sandy Hook Elementary School shooting, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/David Goldman)

  • People wait in line to enter Newtown High School for a memorial vigil attended by President Barack Obama for the victims of the Sandy Hook Elementary School shooting, Sunday, Dec. 16, 2012, in Newtown, Conn. A gunman walked into Sandy Hook Elementary School in Newtown Friday and opened fire, killing 26 people, including 20 children. (AP Photo/David Goldman)