An angry President Obama scolded the U.S. Senate for rejecting a bill expanding federal background checks to more firearms buyers.

Mark Barden, parent of a Sandy Hook School shooting victim, speaks about Senate defeat of increasing backgroud checks (White House)

Flanked by former Representative Gabrielle Giffords (D), Vice President Joe Biden and several families of victims of the Sandy Hook Elementary School shooting says the Senate's opposition to a bill that would have expanded background checks for gun buyers marks a "shameful day" in Washington. He says a minority of senators decided "it wasn't worth it" to protect the nation's children.

Obama spoke in the Rose Garden shortly after the Senate vote. It marked a major blow to the gun control push Obama started in the wake of December's shooting at a Newtown, Conn., elementary school.

"This effort isn't over," President Barack Obama vowed, urging supporters to get better organized as the bill's opponents have.

The president pinned the blame on Senate Republicans for the measures failure, though five Democrats also opposed the plan.

Oama was introduced by Mark Barden,  the father of a 7-year-old killed in the shooting.

The Associated Press contributed to this story