Flanked by people affected by gun violence, including former congresswoman Gabrielle Giffords, and introduced by the father of one of the Sandy Hook victims, a defiantly angry President Obama tore into the 46 United States senators who voted against a bill to expand background checks, preventing it from reaching the 60-vote threshold needed to break the threat of a Republican filibuster.

Speaking from the White House Rose Garden, Obama called Wednesday “a pretty shameful day for Washington” and accused the gun lobby, namely the National Rifle Association, of having “willfully lied about the bill,” according to a transcript of the speech compiled by Time.

Obama pledged not to give up on the issue, calling Wednesday’s setback only “round one” and said he could “do more if Congress gets its act together.”

The bill was crafted by Democratic Sen. Joe Manchin of West Virginia, who has an ‘A’ rating from the N.R.A. and actually fired a rifle in one of his campaign ads, and Republican Sen. Patrick Toomey of Pennsylvania, a Tea Party favorite. It would have expanded background checks on purchases from gun shows and private sales, but explicitly banned the creation of a federal registry, a major fear of a certain element of gun owners.

Even though it was a bipartisan bill that Obama said “showed respect for gun owners, and it showed respect for the victims of gun violence,” the Manchin-Toomey legislation failed on procedural grounds in the Senate with 54 percent support.

Giffords, whose promising career in Congress ended when she was shot in the head two years ago at a public event in her hometown of Tucson, Ariz., has reinvented herself as an advocate for gun law reform, having started an organization with her husband, ex-astronaut Mark Kelly, called Americans for Responsible Solutions.

Giffords and Kelly are supporters of gun rights and remain gun owners, but they have been strong advocates of expanding background checks. The man who was convicted of shooting Giffords, Jared Loughner, had shown signs of mental instability and might not have passed a more expansive background screening.

Shortly after the Senate vote and Obama’s speech, Giffords released a scathing op-ed she penned for for the New York Times. She accused the dissenting senators of “bringing shame on themselves” and asked for voters to penalize them.

“Speaking is physically difficult for me. But my feelings are clear: I’m furious. I will not rest until we have righted the wrong these senators have done, and until we have changed our laws so we can look parents in the face and say: We are trying to keep your children safe. We cannot allow the status quo — desperately protected by the gun lobby so that they can make more money by spreading fear and misinformation — to go on.

I am asking every reasonable American to help me tell the truth about the cowardice these senators demonstrated. I am asking for mothers to stop these lawmakers at the grocery store and tell them: You’ve lost my vote. I am asking activists to unsubscribe from these senators’ e-mail lists and to stop giving them money. I’m asking citizens to go to their offices and say: You’ve disappointed me, and there will be consequences.”

According to an April 4 Quinnipiac poll, 91 percent of Americans support universal background checks on gun purchases. However, 53 percent of gun owners believe such checks could lead to confiscation of legal guns.

Despite the Manchin-Toomey bill explicitly addressing that concern, it could draw only token Republican support.

Read more of Neon Tommy’s coverage of gun control here.

Reach Executive Producer Matt Pressberg here.