(CBSNews.com) - In a major setback for gun control advocates, the Senate Wednesday voted down a key amendment to the embattled Democratic gun bill, signaling the increasingly dim prospects of any meaningful legislative action aimed at strengthening America's gun laws.
The bipartisan Manchin-Toomey amendment, a background check expansion devised by Sens. Joe Manchin, D-W.Va., Pat Toomey, R-Pa., and a handful of other lawmakers, earned only 54 votes, falling six votes short of the 60-vote threshold. Vice President Joe Biden, who led the Obama administration's months-long lobbying effort on behalf of stronger gun laws, presided over the vote.
The failure of the Manchin-Toomey amendment, which was crafted over weeks of negotiation with the aim of attracting Republican support in both the Senate and, eventually, the House, could serve as the death knell for the larger piece of legislation, though it's possible Reid will bring new amendments to the floor at a later date.
A slew of other amendments, including the assault weapons ban, also failed to gain the necessary traction.
In the hours before the vote, Organizing for Action, an advocacy group that works on behalf of the president's legislative agenda, urged voters to call their senators in support of expanded background checks. The Democratic National Committee (DNC) sent out similar emails, specifically targeting a group of Republican senators who had at one point appeared amenable to the Manchin-Toomey language. Meanwhile, a pro-gun group that had previously backed the ban pulled its support.
In the end, four Republicans voted in favor the Manchin-Toomey amendment, and four Democrats voted against it, excluding Senate Majority Leader Harry Reid, D-Nev., who switched his vote from yea to nay for procedural reasons.
Of the Democrats who voted against the amendment, Sens. Max Baucus, D-Mont., Mark Begich, D-Alaska, Heidi Heitkamp, D-N.D., and Mark Pryor, D-Ark. all are up for election next year in 2014 in "red" states, barring Heitkamp, who isn't up for re-election until 2018.
But the pattern is not universal: Sen. Mary Landrieu, D-La., a "red state" Democrat, voted in its favor. Of the Republicans who voted for the measure -- Sens. Susan Collins, R-Me., Mark Kirk, R-Ill., John McCain, R-Ariz., and Toomey -- only Collins is up for re-election next year. She, Toomey, and Kirk all represent Democratic-leaning states.
McCain, one of those who broke with the GOP ranks, delivered a vehement defense of the bipartisan amendment in debate over the bill, and disputed the argument, touted by his fellow Republicans, that it would strip Americans of their Second Amendment rights.
"For over three decades in Congress, I have built as strong a record as anyone in this body in defending the Second Amendment. I have consistently opposed the efforts of anti-gun activists to ban guns and ammunition, staunchly defending the Constitutional rights that Arizonans hold dear," McCain said, continuing with a list citing his pro-gun credentials. But, he added, "Just as I have long defended the Second Amendment to the Constitution, I have also long believed that it is perfectly reasonable to use available tools to conduct limited background checks, as this amendment prescribes, to help ensure that felons and the mentally-ill do not obtain guns they should not possess."
"In my view, such background checks are not overly burdensome or unconstitutional," McCain said.
Toomey, R-Pa., who spent weeks working with Manchin on the language of the amendment, made a final push for the amendment just minutes before it was shot down. After touting his "A" grade NRA rating and his commitment to upholding the Second Amendment, Toomey argued that "the Second Amendment does not apply equally to every single American," and that his measure would just help keep guns out of the hands who have lost their rights to tote guns.
"The goal was to see if we can find a way to make it a little more difficult for the people who have no legal right to have a gun, for them to obtain one," he said. "There is absolutely no way that this can be construed as an infringement on our Second Amendment rights."
Speaking passionately in remarks after the votes, President Obama lamented the "shameful" events in Congress, and pledged the fight would not end with today's Senate action.
"Sooner or later, we're going to get this right. The memories of these children demand it and so do the American people," said Mr. Obama, who was standing alongside families of the Newtown victims as well as former Rep. Gabby Giffords, who was shot in the head two years ago in the Tucson shootings.
In a flurry of statements released after the vote, Democrats and gun safety advocates concurred with the president's disappointment.
New York City Mayor Michael Bloomberg, the co-founder of Mayors Against Illegal Drugs, issued a scathing statement calling the amendment's failure a "damning indictment of the stranglehold that special interests have on Washington."
"More than 40 U.S. senators would rather turn their backs on the 90 percent of Americans who support comprehensive background checks than buck the increasingly extremist wing of the gun lobby," Bloomberg wrote. "Democrats - who are so quick to blame Republicans for our broken gun laws - could not stand united. And Republicans - who are so quick to blame Democrats for not being tough enough on crime - handed criminals a huge victory."
Giffords, who after the Tucson shootings founded a gun control advocacy group, emailed supporters shaming lawmakers for doing "nothing" to strengthen gun laws in the wake of violence that wounded her and killed others.
"Over two years ago, when I was shot point-blank in the head, the U.S. Senate chose to do nothing. Four months ago, 20 first-graders lost their lives in a brutal attack on their school, and the U.S. Senate chose to do nothing," Giffords wrote. "It's clear to me that if members of the U.S. Senate refuse to change the laws to reduce gun violence, then we need to change the members of the U.S. Senate."
Meanwhile, the National Rifle Association (NRA), the pro-gun lobby that has been fighting any legislation that would make gun laws more restrictive, released a statement doubling down on its critique of the Manchin-Toomey amendment.
"This amendment would have criminalized certain private transfers of firearms between honest citizens, requiring lifelong friends, neighbors and some family members to get federal government permission to exercise a fundamental right or face prosecution," said Chris Cox, an NRA lobbyist, in the statement. "As we have noted previously, expanding background checks, at gun shows or elsewhere, will not reduce violent crime or keep our kids safe in their schools."
Anthony Salvanto contributed to this report
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