WASHINGTON — After the Sandy Hook school massacre in 2012, President Barack Obama turned to his vice president, Joe Biden, to lead a push for new gun laws.

It was a natural choice since Biden had written the assault weapons ban, long supported expanding background checks and earned "F" ratings from the National Rifle Association while in Congress.

"As the president knows, I've worked in this field a long time in the United States Senate," Biden said at the time.

As Biden prepares to launch his 2020 presidential run on Thursday, guns are an area of his decades-long record in public life in which he has been consistently in line with the values of today's Democratic Party.

But still, potential political dangers lurk, even on his signature issue — including a vote in favor of a 1986 bill that the NRA has called "the law that saved gun rights" in America.

The Firearm Owners Protection Act, which passed Congress overwhelmingly, overturned six Supreme Court rulings and numerous regulations, leaving a lasting legacy as one of the most consequential gun laws of the past century and as a key political boost for the burgeoning gun rights movement.

The measure allowed dealers to sell rifles, shotguns and ammunition through the mail, and, eventually, the internet. It limited federal inspections of firearms dealers while allowing them to sell guns at gun shows, which helped them grow in size and popularity. And it made it easier for private collectors to sell guns without obtaining a federal dealers' license, which would play a role in what later became known as the "gun show loophole." (It also banned machine guns, thanks to an amendment slipped in by House Democrats at the last minute.)

But it was a different era decades ago, when compromise was common in the Senate and guns were less of a partisan and emotional issue than they are today. Things look very different in 2019, when Democrats vie with one another to take the toughest line on firearms.

"I'm one of the last of the generation of gun lobbyists who used to work with a lot of Democrats," said Richard Feldman, a former NRA lobbyist who worked on the bill and later broke with the group. "I actually think Biden's more sensible than any other of the major candidates because he's been around long enough.”

Sen. Joe Biden, chairman of the Senate Judiciary Committee, holds a TEC-9 semi-automatic weapon during a hearing on assault weapons at the Capitol on Aug. 3, 1993. Barry Thumma / AP file

At the time, Congress had not done anything big on firearms since the Gun Control Act of 1968, which was passed in response to the assassinations of Martin Luther King Jr. and John and Robert Kennedy. As its name suggests, the law was not a win for gun rights advocates.

The NRA desperately wanted a victory and got one when President Ronald Reagan signed into law the Firearm Owners Protection Act, which had finally passed Congress seven years after its introduction.

"In 1986, the gun rights movement really came into its own when it established its power to win on the offensive," David Hardy, a conservative lawyer and author wrote in a 2011 article for the NRA.

Gun rights advocates argued existing law needed to be changed because it was turning well-meaning gun owners into felons for minor record-keeping errors and innocent ignorance of complicated state laws.

But as long as Sen. Ted Kennedy, D-Mass., chaired the Judiciary Committee, they knew reform had no chance.

Then, in 1982, Republicans won control of the Senate and Sen. Strom Thurmond, the South Carolina conservative, took the gavel on Judiciary, and Biden became the ranking Democrat on the panel.

While some liberals fought the legislation, Biden and other Democrats — including initially Kennedy, though he later opposed the bill — helped find a compromise that maintained rules on handguns while eliminating all exemptions on interstate sales or transportation of "long guns," including rifles and shotguns.

"I believe the compromises that are now a part of this bill have resulted in a balanced piece of legislation that protects the rights of private gun owners while not infringing on law enforcement's ability to deal with those who misuse guns or violate laws," Biden said at the time.

"During my 12 and a half years as a member of this body, I have never believed that additional gun control or federal registration of guns would reduce crime. I am convinced that a criminal who wants a firearm can get one through illegal, nontraceable, unregistered sources, with or without gun control," he continued.

With support from the top members of each party on the Judiciary Committee, the panel voted unanimously to send the bill to the full Senate.

John Snyder, the chief lobbyist for the Citizens Committee for the Right to Keep and Bear Arms, praised Thurmond and Biden for "reaching agreement on this principle," noting at the time that they had voted "to eliminate a good 75 percent of the onerous and burdensome Gun Control Act."

Vice President Joe Biden speaks at a meeting with gun violence survivors and gun safety advocacy groups in the Eisenhower Executive Office Building on Jan. 9, 2013. Chip Somodevilla / Getty Images file

On the Senate floor, the bill passed by a lopsided 79-15, with a roll call that would be difficult to imagine today.

The "nay" column included liberal Democrats like Kennedy, John Kerry of Massachusetts, Gary Hart of Colorado, Daniel Patrick Moynihan of New York and Chris Dodd of Connecticut, but also the moderate Republicans John Chafee of Rhode Island and Charles Mathias of Maryland.

Meanwhile, Biden had plenty of company from other well-known Democrats among the "yeas," including Al Gore of Tennessee, George Mitchell of Maine, John Glenn of Ohio and Pat Leahy of Vermont. Harry Reid of Nevada, then a congressman, voted for the bill in the House, where the main fight actually took place.

Critics say the law has created backdoors for shady gun sales while tying the hands of the Bureau of Alcohol, Tobacco and Firearms. It's had some unforeseeable consequences as well, especially by creating a thriving online market for guns and ammo, which has at times been exploited for nefarious purposes, including by at least one mass shooter.

Bill Russo, a spokesperson for Biden, said the former vice president's record fighting the NRA is strong and he continues to fight for gun reform.

"Cherry-picking an out of context quote from 1986 doesn't even begin to address Joe Biden's unparalleled record on gun safety," Russo said. "Let's be clear on the facts: Joe Biden took on the NRA and won — twice. He led the way to pass the Brady Bill in 1993, establishing the background check system that has kept guns out of the hands of millions of dangerous individuals. In 1994, he also authored the bill banning weapons of war — assault weapons and high capacity magazines — for a decade."

And he noted that Biden's effort after Sandy Hook led to more than two dozen executive actions on gun violence.