Updated 7:30 p.m. ET
Senate Majority Leader Harry Reid, D-Nev., announced Thursday that he's pulling the gun control bill from the floor, to "hit pause" and return to the bill at a later date after a compromise background check amendment was blocked Wednesday.
Reid offered no timetable for renewing the drive to enact legislation that President Obama has placed near the top of his domestic agenda.
"We should make no mistake, this debate is not over," Reid said Thursday on the Senate floor.
"I've spoken to the president, he and I agree that the best way to keep working towards passing a background check bill, is to hit pause and freeze the background check bill where it is."
"We are going to come back this bill," he added.
Mr. Obama, angry and defiant over the defeat, is vowing to fight on. And the NRA says it is taking him seriously. "We are prepared for a very long war and a very expensive war," association spokesman Andrew Arulanandam said Thursday.
The NRA's success is built on the passion of gun advocates, activists on both side of the debate agree. That's how they were able to defeat expanded background checks despite polling that shows up to 90 percent of Americans support the idea.
Sen. Joe Manchin, D-W.Va., who along with Sen. Pat Toomey, R-Pa., and a handful of other lawmakers devised a bipartisan amendment to expand background checks on gun purchases, told CBS News correspondent Chip Reid on Thursday their fight is far from over. The amendment earned only 54 votes Wednesday, falling short of the 60-vote threshold.
"It's just a good, solid bill that had a lot of people working for months to try to put together - and it's one worth continuing to fight for," Manchin said.
The senator guessed that if his colleagues had voted their consciences - "if there was no scoring and no political pressure on the outside" - the proposal would have gotten as many as 70 votes from the 100-member body: "The vote failed, I think that basically everything was in jeopardy as you saw yesterday you know nothing was moving where people were just entrenched," he said. "And I think when some organizations the NRA and other gun organizations said, 'We're going to score it,' you know and people said, 'Oh my goodness.'"
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, served as the death knell for the larger piece of legislation.
Speaking passionately in remarks after the votes, Mr. Obama lamented the "shameful" events in Congress, and pledged the fight would not end.
"The gun lobby and its allies willfully lied about the bill... [T]hose lies upset an intense minority of gun owners, and that in turn intimidated a lot of senators. And I talked to several of these senators over the past few weeks, and they're all good people," Mr. Obama said. "But the fact is most of these senators could not offer any good reason why we wouldn't want to make it harder for criminals and those with severe mental illnesses to buy a gun. There were no coherent arguments as to why we wouldn't do this. It came down to politics."
"So all in all, this was a pretty shameful day for Washington. But this effort is not over," said Mr. Obama, who was standing alongside families of the Newtown victims as well as former Rep. Gabrielle Giffords, who was shot in the head two years ago in the Tucson shootings. "Sooner or later, we're going to get this right. The memories of these children demand it and so do the American people."
Sen. John Cornyn, R-Texas, responded to the president Thursday saying, "When good and honest people have honest differences of opinion about what policies the country should pursue about gun rights...the president of the United States should not accuse them of having no coherent arguments or of caving to the pressure."
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."