Story highlights "I'm not aware of what that would be," Sanders said

It's the 5th anniversary of the massacre

Washington (CNN) Five years after a gunman killed 20 children and six adults at Sandy Hook Elementary School in Connecticut, the White House downplayed efforts to prevent mass shootings, insisting there was no single solution to increasingly deadly violence.

"I'm not aware of what that would be," Sanders said during a daily news briefing. "But we want to look for every opportunity, every way possible, that we can to protect American lives. And we are going to continue doing that."

Gun control groups and Democrats maintain that a ban on so-called assault weapons and tighter controls on background checks could prevent deadly weapons being used to massacre Americans. Efforts to pass those items through Congress have failed, however.

Pressed on efforts underway within the administration to curb gun violence, Sanders cast doubt on the efficacy of legislation that would make it harder to obtain firearms.

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