Still, the gun lobby had no clear sense initially of how its efforts would be waged, and to what end. On Jan. 10, 2013, Biden hosted a meeting in his Executive Office Building suite with several Second Amendment supporters, including the veteran N.R.A. lobbyist Jim Baker. When Biden asked if the N.R.A. would consider supporting a ban on assault weapons or high-capacity magazine clips, Baker’s answer was a crisp “no.” But when asked the same thing about universal background checks, Baker equivocated, saying, “I’d have to see what you’re talking about.”

Baker knew this was thorny territory for the N.R.A. Extending background checks to firearms purchases at gun shows and over the Internet, with the aim of making it harder for felons and the mentally ill to acquire weapons, remains popular and not just among liberals. According to a CBS News/New York Times poll taken in the days after the Biden meeting, 92 percent of Americans favored universal background checks. A poll conducted by the Republican pollster Frank Luntz indicated that there was 74 percent approval among self-identified N.R.A. members — in keeping with the 77 percent approval in a survey of hunters commissioned by the Bull Moose Sportsmen’s Alliance. (The N.R.A. dismisses these high numbers but has offered none of its own. Three days after the Biden meeting, the Republican polling firm OnMessage conducted a survey for the N.R.A. of its members on a variety of legislative topics — but was not instructed to ask about universal background checks.) After Newtown, the N.R.A. lobbyists suspected that if the Democrats were to reintroduce Dingell’s 1999 background-checks bill, there would be no political will to oppose it.

In January, Biden’s task force announced its legislative recommendations. These included universal background checks, a ban on assault weapons and limits on magazine capacity. Each initiative would successfully pass through the Senate Judiciary Committee, whose chairman was Patrick Leahy — himself an owner of more than a dozen firearms who has spent time during Vermont winters shooting at large chunks of ice. Though it was clear from the outset that there would never be enough votes in the Senate to pass either an assault-weapons ban or a limit on magazine capacity, progressives were convinced that their moment had arrived on universal background checks. During one meeting between several Democratic senators and some of the Newtown parents in early February, Al Franken of Minnesota openly conveyed the optimism many on his side of the issue were feeling. “There’s not an argument — there aren’t two sides to this,” he said, according to someone who was present. “This is common sense. And that’s the end of it.”

Not every Democrat felt so sanguine. Any bill that made it out of the Senate would face stiff opposition from the Republican-controlled House. Other pressing issues (like immigration) loomed on the legislative calendar, and the Senate majority leader, Harry Reid, had no desire to see the agenda overtaken by gun control. Like Leahy, Reid was a gun owner who was keenly aware of the place firearms hold in American life — and who recognized that not everyone in his party understood this. At roughly the same time that Franken and other Democratic senators were plotting their legislative strategy, their Democratic counterparts in the House met for an annual retreat in Leesburg, Va. Among the gathering’s main events was a seminar on how to talk to voters about firearms and gun legislation. But not one of the four panelists — a Yale law professor, a political reporter, a former Orlando police chief who ran for Congress on the Democratic ticket and the veteran Beltway strategist Anita Dunn — could claim a true appreciation of American gun culture. According to two attendees, when Dunn was describing the desirability of background checks, she used the word “registration” — thereby conjuring up the specter of a national registry of all licensed guns, a notion that is abhorrent to many gun owners, who fear that registering firearms with a federal agency would make it easier for the government to one day confiscate them. “She kept using the R-word,” one attendee recalls. “And what I took away was that nobody in the Democratic Party knows how to talk about this.”

Joe Manchin shared the concern that the Democrats who were leading the charge on gun legislation didn’t understand how deeply people care about guns and needed to if they were ever to get anything passed. By January the universal background-checks legislation was being spearheaded in the Senate by Charles Schumer, a liberal from New York City. “Joe, I didn’t know anybody who owned a gun when I grew up,” Schumer said to Manchin, who replied, “Chuck, I didn’t know anybody who didn’t own a gun.” Schumer’s bill contained no provisions that might attract the support of gun owners, a fatal omission in Manchin’s view. “The bill Chuck Schumer dropped was one that I didn’t think anyone from a gun state would or should support,” Manchin told me. “So I reached out to the N.R.A. and said, ‘Let’s have an alternative.’ ”

In early March, Chris Cox and Jim Baker came to Manchin’s office to hear him out — the first of several face-to-face meetings they would have that month. Manchin knew that the lobbyists were never going to embrace universal background checks. His hope was simply that they would not fight him. To win their neutrality, Manchin had all sorts of ideas for an N.R.A.-friendly bill. In his version, firearms dealers would, for the first time since 1968, be allowed to sell handguns across state lines, including at out-of-state gun shows. Members of the military and their spouses could purchase guns in their native state and in the state where they were stationed. Such provisions had been championed by the gun group for years. “I told the N.R.A., ‘When will you ever have a time when liberals who hate us even having a gun actually vote for something that protects and enhances our rights — and all we ask for in return is to tighten up loopholes in legislation that’s already there?’ ” he said. “Absolutely, I said that to them. Many, many times.”

Among the N.R.A.'s most-activist members, however, there is a powerful suspicion that one restriction will open the door to more, each new limit leading inexorably to a time when there will no longer be a right to bear arms. Throughout March, the N.R.A. employed the familiar mechanics of lobbying the dozen or so senators — including Democrats facing tough re-election battles in 2014 like Mary Landrieu of Louisiana and blue-state Republicans like Kelly Ayotte of New Hampshire — who had not yet decided whether they would support the bill. They pressed for face time with the senators, cozied up to their aides and urged N.R.A. members in their states to harangue the Washington offices. Cox and Baker were aware that the senators were also feeling pressure from the White House and gun-safety groups — and, of course, from Joe Manchin, a fellow N.R.A. member and sportsman who actively sought to allay the fears of red-state legislators that his bill would be impossible to sell back home. Recognizing, for example, that a chief talking point of the gun lobby was that universal background checks might enable a government agency to compile a national registry, he added a section that would make the attempt to do so punishable by a 15-year prison sentence. By early April, Manchin found a willing Republican co-sponsor: Pat Toomey of Pennsylvania, the former president of the fiscally hawkish Club for Growth who, like Manchin, had received an A rating from the N.R.A. (Toomey hailed from a blue state and, says someone closely involved in the legislative strategy, “he needed something to show to more moderate voters in Pennsylvania that he’s not an ideologue.”)