WASHINGTON -- Never much known for restraint, Joe Biden 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 semi-automatic rifle and declared, "This is my baby."
Mr. Biden, then a U.S. senator from Delaware 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 the United States' 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 Barack 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 Sen. 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 NRA, to put it mildly."
As far as the NRA 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 NRA 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 semi-automatic rifles, more than 3 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 weapon 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.
In the end, it passed, in significant part because of Mr. Biden.
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.