The Senate on Wednesday rejected a bipartisan amendment that would have expanded background checks on gun purchases, a blow to advocates calling for more strict firearm laws after the mass shootings in Newtown, Conn., late last year.

The measure, the product of intense negotiations between Pennsylvania Republican Sen. Pat Toomey and West Virginia Democratic Sen. Joe Manchin, would have extended background check requirements on gun owners. It needed 60 votes to pass, but failed 54-46.

Democrats voting against the amendment were Mark Begich of Alaska, Heidi Heitkamp of North Dakota, Mark Pryor of Arkansas and Max Baucus of Montana. (Sen. Harry Reid of Nevada switched his vote to no at the end, a procedural tactic that allows him to bring it up for a vote later.) In addition to Toomey, Republicans who supported the amendment were Sens. Mark Kirk of Illinois, Susan Collins of Maine and John McCain of Arizona.

Scores of onlookers filled the Senate gallery to watch the vote. When Vice President Joseph Biden read the final tally and announced the amendment had not passed, Patricia Maisch, who helped disarm the man who shot former Rep. Gabrielle Giffords in Tucson in 2011, yelled, "Shame on you!" before walking out of the chamber.

When the vote finished, families with loved ones killed by gun violence who had attended the vote consoled one another outside the Senate floor. Democratic Sens. Chuck Schumer of New York, Reid and Manchin joined them later. The parents of Jessica Ghawi, who was murdered last year in Aurora, Colo., during the November shooting at a movie theater, handed Reid a picture of their deceased daughter. When Ghawi spoke to the press, he placed the photo on the lectern and left it there so that speakers after him could see her picture.

"In the beginning of this process, I made it clear that any legislation that passes the Senate must include background checks to be effective. That is still the case," Reid told reporters. "I'm going to do everything that I can to fight for meaningful background check legislation. The fight has just begun. It's not going away."

Story continues

After Reid's remarks, Sen. Richard Blumenthal of Connecticut, the state where 27 people—most of them children—were killed in Newtown last year, approached the lectern.

"Today was a heart-breaker," Blumenthal said. "Probably the saddest day of my years in public life."

Despite the setback, the senators vowed that they would continue to press for overhauling the nation's federal gun laws.

At the White House, President Barack Obama spoke in the Rose Garden alongside family members who lost loved ones at the Sandy Hook Elementary School shooting in Newtown, Conn., Rep. Gabrielle Giffords and Vice President Joe Biden.

Obama chastised Congress, saying, “All in all, this was a pretty shameful day in Washington.”

The president placed most of the blame on Republicans, 90 percent of whom, he said, voted against the Manchin-Toomey amendment. “It came down to politics,” Obama said in the Rose Garden. “They caved to the pressure.”

He also blamed the gun lobby for spreading “misinformation” about the amendment, saying the lobby and its allies “willfully lied about the bill” and claimed it would work to establish a gun registry.

The president asked all Americans who support background checks to express their disappointment to their representatives in Washington, adding that those who want gun reform “have to sustain the same passion about this” as the powerful gun lobby.

He vowed to keep up the fight. “I see this as just round one,” Obama said. He added that his administration will continue to work towards reducing gun violence, but “we can do more if Congress gets its act together.”

Additionally, the president thanked Toomey and Manchin for their “courage” in introducing the amendment.

Throughout Obama's remarks, some of the family members of the Newtown victims—including Jimmy Greene, Nicole Hockley, Jeremy Richman, Neil Heslin, Mark Barden, Jackie Barden, Natalie Barden and James Barden—were visibly emotional. Obama and Biden comforted some of them.

The president also addressed accusations from Republican Sen. Rand Paul and others that he's using Newtown family members as “props” in the gun control debate.

“Are they serious?” he asked, and challenged critics to question the rights of family members of victims to voice their opinions in the gun debate.