Obama: Dec. 14 'worst day of my presidency'

Supporters of gun control gather on Pennsylvania Avenue in front of the White House in Washington, Friday, Dec. 14, 2012, during a vigil for the victims of the shooting at Sandy Hook Elementary School in Newtown, Ct., and to call on President Obama to pass strong gun control laws. (AP Photo/Charles Dharapak)

President Barack Obama greets Connecticut Gov. Dannel P. Malloy during an interfaith vigil for the families and residents affected by the Sandy Hook Elementary School shooting at Newtown High School in Newtown, Conn., on Sunday, Dec. 16, 2012.

President Barack Obama addresses the nation during an interfaith vigil for the families and residents affected by the Sandy Hook Elementary School shooting at Newtown High School in Newtown, Conn., on Sunday, Dec. 16, 2012.

Sen. Joseph Lieberman greets people before President Barack Obama speaks in the Newtown High School auditorium on Sunday, Dec. 16, 2012.

Sen. Richard Blumenthal, left, stands alone as U.S. Congresswoman-elect Elizabeth Esty greets people before President Barack Obama speaks in the Newtown High School auditorium on Sunday, Dec. 16, 2012.

President Barack Obama wipes his eye as he speaks about the school shooting in Newtown, Conn., Friday, Dec. 14, 2012, in the briefing room of the White House in Washington. (AP Photo/Charles Dharapak)

President Barack Obama walks to his car after arriving at Bradley Air National Guard Base to attend an interfaith vigil for the victims of the Sandy Hook Elementary School shooting in Newtown on Sunday, Dec. 16, 2012 in East Granby, Conn. A gunman walked into Sandy Hook Elementary School in Newton, Conn., on Friday and opened fire, killing 26 people, including 20 children. (AP Photo/ Evan Vucci)