Soon after retiring from a three-decade career in law enforcement, David Chipman used his first op-ed as a private citizen to advocate for an unusual cause: Senate confirmation of the director of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Since the Senate changed rules to require that the ATF director undergo a confirmation process, no one had been able to get through the gantlet to win a vote to fully take over the agency that regulates firearms.

“What we need instead is a full-time director and a fully funded agency with a proactive and aggressive approach to its mission, equipped to coordinate with other law enforcement agencies,” Chipman wrote in 2013 before the first successful confirmation of an ATF director.

On Wednesday, Chipman’s previous words proved prophetic as he appeared before the Senate Judiciary Committee in his bid to become only the second ATF director to win confirmation by the full Senate.

With Chipman’s 25 years at ATF, in which he rose through the ranks and served as an investigator of terrorist attacks in New York City and Oklahoma City in the 1990s, his supporters think he has a unique background fitted to run the somewhat rudderless agency.

He more recently served as a policy adviser at Giffords, the gun violence group founded by former congresswoman Gabrielle Giffords (D-Ariz.), which has lobbied for stricter gun laws such as universal background checks in firearm sales.

That has given Chipman credibility among Democrats who are looking for a more active regulatory agency.

“There’s always sort of the chill that exists on ATF’s work because without a leader to answer for any new directions they’re taking, the agency never wants to do anything that might respond to new developments, new trends or new threats. So the agency gets frozen in time,” Sen. Chris Murphy (D-Conn.), a leader on gun issues since the 2012 mass shooting at a Connecticut elementary school, said Tuesday.

But that background also gives pause to Senate conservatives who have shown no interest in empowering an agency they believe will undercut the Second Amendment — an agency that has been cast in many false conspiracies among right-wing gun rights activists.

For more than six years, the post of ATF director has rotated between a pair of acting directors, and the Trump administration never prioritized the position. Its only nominee for the post, Chuck Canterbury, a former president of the national Fraternal Order of Police, came under political fire from Democrats because his nomination looked like a political payoff for the FOP’s endorsement of Trump’s 2016 candidacy.

But conservative Republicans also opposed Canterbury as insufficiently pro-gun, questioning his support for banning assault rifles. In the past 15 years, ATF has had a Senate-confirmed director for just two years.

During Wednesday’s hearing, Sen. Tom Cotton (R-Ark.) picked through Chipman’s many statements to the media and writings to note his past support for a ban on assault weapons, demanding a definition for such a firearm.

When the nominee explained the ATF’s definition, Cotton replied, “I’m amazed that that might be the definition of assault weapon. That would basically cover every single modern sporting rifle.”

Chipman appeared before the Judiciary Committee with several nominees for domestic law enforcement posts, including President Biden’s nominees to run the Drug Enforcement Administration and the criminal division at the Justice Department.

In an emotional moment to which gun critics point to illustrate ATF’s importance, Sen. Dianne Feinstein (D-Calif.) informed Chipman that while he was testifying, an employee at a San Jose light-rail facility had opened fire, killing at least eight.

“I wasn’t aware of that. If I’m confirmed as ATF director, one of our priorities at ATF will be focusing on gun trafficking — the unlawful transfer of legal guns to criminals,” Chipman said.

With the support of 50 members of the Democratic caucus, Chipman could win confirmation just by holding them together for a tiebreaking vote by Vice President Harris. But Democrats are still trying to win some support among Republicans who have been involved in talks led by Murphy and Sen. Joe Manchin III (D-W.Va.) about background-check legislation. Among the Republican senators involved in those talks: Patrick J. Toomey (Pa.) and Susan Collins (Maine).

On Tuesday, Collins noted that her state’s most prominent gun rights organization has asked her to oppose Chipman’s confirmation.

“So I need to take a hard look at him,” she said, adding that she has grown tired of the endless line of acting ATF directors who do not all respond to Senate oversight the same way.

In the 1990s, Chipman was an investigative responder, digging through the rubble of the first World Trade Center bombing in 1993 and then at a federal building in Oklahoma City two years later — a formative experience that also was a career-defining moment for Attorney General Merrick Garland when he was a federal prosecutor.

Chipman also investigated arsons at Black churches in Alabama and advanced to senior ATF positions. But in the latter stage of the Bush administration and early years of the Obama administration, ATF was left to wither without a confirmed leader.

“During my final six years with ATF, I served five acting directors. Morale was unsteady, and the agency was more chaotic than orderly. It’s simply unacceptable that ATF isn’t empowered to fight and stop crime,” Chipman wrote in 2013, soon after retiring.

Some supporters of Chipman have talked about his becoming the “Dr. Fauci of gun violence” — a trusted public figure who can explain how guns are trafficked into the hands of bad actors, in the way that Anthony S. Fauci became a national figure explaining how the coronavirus was spread and what steps could be taken to constrain it. Fauci, however, has become a target of some conservatives for advocating public health restrictions during the pandemic that they oppose, such as mask-wearing and limiting the number of people at indoor venues or events.

Chipman’s friends at Giffords and other gun violence groups want to see ATF issuing more reports that explain the flow of guns and cracking down on gun dealers whose weapons end up in the hands of criminals.

“He’s ready to lead on Day One,” said Peter Ambler, executive director of Giffords.

This month, Garland announced a new rule requiring retailers to run background checks before selling “ghost gun” kits — which allow someone to readily make a gun at home — and also mandating serial numbers on a firearm’s structural components. That is to ensure that ATF can trace guns used in crimes.

If confirmed for the job, Chipman will have to try to unwind the conspiratorial mythology that has become attached to ATF among gun activists dating to its participation in the 1993 siege at the Branch Davidians compound in Waco, Tex.

One gun website recently showed a picture of the charred site and repeated a false claim that Chipman posed for a picture in front of it.

He was never at Waco.

In this mythology, ATF agents are the “jack booted thugs” who are coming to seize citizens’ guns.

In reality, ATF is similar in size to the U.S. Capitol Police.

“It’s important for him to be able to explain what ATF does and what it doesn’t do,” Murphy said. “It’s to dispel this mythology that there’s some hidden agenda at ATF to confiscate law-abiding citizens’ weapons.”