WASHINGTON -- Never much known for restraint, Joseph R. Biden Jr. did not hold back during a presidential primary debate in 2007 when a voter asking about gun rights in a recorded video displayed a fearsome-looking semiautomatic rifle and declared, "This is my baby."
Mr. Biden, then a Delaware senator in a dark-horse bid for the White House, shook his head. "I tell you what, if that's his baby, he needs help," he said. "I think he just made an admission against self-interest. I don't know if he's mentally qualified to own that gun."
The candidate's blunt, dismissive remark cheered one side of America's long-polarized debate about guns and alienated the other. But it overlooked the salient reality that the rifle-toting voter was able to buy it legally even under a law that theoretically banned assault weapons and was co-written by Mr. Biden.
Five years later, that same type of weapon, a Bushmaster AR-15, is at the heart of a renewed national conversation about gun laws because it was used this month by the mass killer in Newtown, Conn. For Mr. Biden, now the vice president, the moment offers a second chance as he drafts a legislative response for President Obama that would reinstate his expired assault weapons ban, while also applying lessons from the last time around to make it more effective.
A president intent on pressing Congress to restrict access to high-powered guns could hardly find a more seasoned figure to take charge of the effort. Mr. Biden, who owns two shotguns, brings decades of experience and plenty of scar tissue from past battles with the National Rifle Association to frame recommendations that Mr. Obama wants ready by next month.
"He's basically been doing this for a little over 30 years," said former Senator Ted Kaufman of Delaware, a longtime Biden adviser who was appointed to fill out his term. "I really do believe there isn't anybody in America who has a better chance of getting this done by Jan. 15 than he does, not just because of his background in guns but because he's not politically intimidated by the N.R.A., to put it mildly."
As far as the N.R.A. is concerned, Mr. Biden is an ideologue whose mind is already made up about the "conversation" he is now supposed to lead.
"This is somebody who's bombastic and really does think that anybody who disagrees with him is not only wrong but crazy," David Keene, the N.R.A. president, said in an interview. "That's his style."
Mr. Biden, he added, has not reached out to his group and has shown contempt for gun owners who value their Second Amendment rights. "His debate response and how he's acted as a legislator indicates that he not only doesn't understand it but doesn't have any desire to understand it," Mr. Keene said. "Joe is not a nuance character. He knows what he knows, and he doesn't need to be told that other people think differently than he does."
What Mr. Biden knows is that gun control is not only a fiercely emotional topic for many Americans but also a tricky area for legislation. The assault weapons ban he helped pass in 1994 was written narrowly enough that it allowed plenty of guns to still be sold. Moreover, a 10-year expiration clause was added as a compromise. Democrats went on to lose control of Congress that fall, a defeat that many attributed to the gun law, leaving the party skittish ever since.
This time, Mr. Biden wants to tighten the strictures, but to succeed he needs to get legislation through a Republican-controlled House. And even if he and Mr. Obama can persuade Congress to ban the sale of new semiautomatic rifles, more than three million AR-15 rifles are already in private hands, according to the National Shooting Sports Foundation.
First elected to the Senate in 1972, Mr. Biden had a long interest in passing crime legislation, and gun control eventually became part of his proposals. An assault weapons ban he wrote in the 1980s failed in Congress, but by 1994, as he put together a comprehensive crime package, a new Democratic senator, Dianne Feinstein of California, wanted to try again. Burned after so many failures, Mr. Biden was skeptical.
"When I told Joe Biden, who was chairman of the Judiciary Committee, that I was going to move this as an amendment on the crime bill, he laughed at me," Ms. Feinstein recalled this month on the NBC program "Meet the Press." "He said, 'You're new here. Wait till you learn.' "
President Bill Clinton's White House and House Democrats worried that the gun ban would end up taking down the entire crime bill, which authorized 100,000 more police officers, expanded the death penalty, built more prisons, cracked down on hate crimes and violence against women, and financed prevention programs.
In the end, it passed, in significant part because of Mr. Biden. "I think there were days the chairman didn't sleep," said Karen Robb, who worked for the committee at the time. "It never would have made it out of the Senate without his help, period. It never would have made it out of conference without him."
To get it through required a compromise. The bill defined an assault weapon as a gun that was able to accept a detachable magazine and that included two or more other combat-type accessories, like a pistol grip, a flash suppressor or a grenade launcher; those with just one accessory were still legal.
The upheaval brought about by the midterm election later that year soured Democrats on gun control, although Mr. Biden survived efforts to defeat him two years later. A Republican-led Congress let the assault weapons ban expire in 2004 amid debate about the effectiveness of the original legislation.
By the time Jered Townsend, the Bushmaster owner from Michigan, recorded his question for the 2007 primary debate, Mr. Biden was one of the few outspoken voices on gun control left among Democratic leaders.
Mr. Obama, running against him, offered a modulated position. He agreed with conservatives that the Second Amendment guarantees an individual right to bear arms -- a view later upheld by the Supreme Court -- but he supported gun control measures like a ban on assault rifles that he considered constitutional.
Mr. Townsend, now 36 years old and a contract writer at a construction company, said he bought the Bushmaster he displayed on television legally during the period that Mr. Biden's ban was in place. "We don't need politicians writing gun laws because they don't know what they're doing," he said in a recent interview.
Mr. Townsend said he owned 13 guns and that he liked the Bushmaster's accuracy when he goes target shooting with his father and friends. "There's somebody on the end of every gun pulling the trigger," he said. "We need to treat that person. The gun's not the problem."
Mr. Biden was at the White House when the Newtown massacre occurred. With the shootings coming just days before the 40th anniversary of the car accident that killed his first wife and baby daughter, an aide said, "all he could think about was those parents getting the same devastating phone call" that he once did.
After Mr. Obama assigned him to develop a response, Mr. Biden followed his 1990s script, inviting law enforcement leaders to the White House to harness their ideas and public credibility. "I've been in Washington over 20 years, and this was unique," said Chuck Wexler, the executive director of the Police Executive Research Forum. "There is a sense of importance and urgency to this issue."
Ms. Feinstein plans to reintroduce the assault weapons bill with a more inclusive definition, banning even those with just "one or more military characteristics." It identifies 120 guns by name whose manufacture and sale would be banned, and it would outlaw certain modifications used to bypass the last law.
Mr. Kaufman acknowledged that actually banning guns was difficult. As soon as one gun is outlawed, another pops up. But he argued that symbolism itself was important. "You send a message," he said, "when you don't do anything."
This article originally appeared in The New York Times.