Though more that 90 percent of Americans support requiring background checks for all gun buyers, it was not enough to convince U.S. legislators. The U.S. Senate Wednesday afternoon voted down the bipartisan Manchin-Toomey amendment, 54 to 46.

The Senate requires 60 votes to get past a filibuster.

Wednesday morning, Sen. Pat Toomey of Pennsylvania said outside groups mischaracterized the bill he introduced with Democrat Sen. Joe Manchin of West Virginia.

The background check amendment had some near-miraculous support. In a videotaped appearance, longtime gun-rights advocate Alan Gottlieb endorsed it in front of an audience at a Portland, Oregon golf club. He said that he doesn't like background checks, but had realized his side needs to stop fighting them.

"It's not a tenable position to take," he said. "We're marching off a cliff with it."

Gottlieb, the founder of the Second Amendment Foundation, claimed to have spent hours helping craft the Toomey-Manchin bill, calling it a "Christmas tree" for the gun-rights movement.

"We just hung a million ornaments on it. We're taking the background check and making it a pro-gun bill," he said, adding, "I think we snookered the other side."

It's possible Gottlieb, and certainly the NRA, took part in writing the legislation, said Robert Spitzer, a professor at the State University of New York in Cortland.

NRA may have contributed to stymied plan

"I think gun-rights folks have had a hand in this legislation, but haven't dictated the terms either," he said shortly before the measure failed in the Senate.

The NRA publicly opposes expanded background checks.

But Spitzer said many of the pro-gun items in the legislation simply reinforce existing law, for example, reaffirming a ban against creating a national gun registry. On the whole, he believed the guns-rights side gained only at the margins.

Ladd Everitt, spokesman for the Coalition to Stop Gun Violence, agreed. The most striking thing to him about Gottlieb's video was his acceptance of background checks. That, Everitt said, is a big risk for a man who has leaned to the right of the NRA.

"He would not have supported this law before Newtown ... There is just no scenario under which Alan Gottlieb would have supported this bill to dramatically expand background checks prior to that time," Everitt said.

Still, under the spotlight, the legislation's momentum sagged. Gottleib pulled back his support on Wednesday.

Toomey not likely to try again on background checks

Toomey expressed frustration with the general gridlock but said he could only encourage people to read the legislation.

"It's 49 pages and it's totally understandable. I just think that when people read what is actually in the bill they will realize it's just common sense," Toomey said.

Any Senate compromise would have faced an even tougher battle in the U.S. House of Representatives, where Republicans are in the majority.

It appears unlikely that Toomey will try again. After the Senate vote, he stated, "It’s not the outcome I hoped for, but the Senate has spoken on the subject, and it’s time to move on."