NBC host David Gregory said that Meet the Press had reached out to every gun rights advocate in the U.S. Senate, but none agreed to come on the political talk show.

"A note here this morning: We reached out to all 31 pro-gun rights senators in the new Congress to invite them on the program to share their views on the subject this morning," he said. "We had no takers."

Two gun control advocates, Sen. Dianne Feinstein (D-CA) and New York Mayor Michael Bloomberg, joined the show on Sunday morning to discuss the tragic shooting at Sandy Hook Elementary School in Newtown, Connecticut. Both called for new laws to restrict access to assault rifles like the one used in the shooting.