Since the position of ATF director became a Senate-confirmed position 15 years ago, the Senate has confirmed a grand total of one person to the job. If Sen. Susan Collins (R-Maine) has her way, that number won’t grow anytime soon. The Bangor Daily News reported:

U.S. Sen. Susan Collins, R-Maine, said she would vote against President Joe Biden’s pick to lead the Bureau of Alcohol, Tobacco, Firearms and Explosives on Monday, making David Chipman’s path to confirmation more difficult. In a statement released by the Sportsman’s Alliance of Maine on Monday, Collins characterized Chipman’s background as “unusually divisive,” saying he had “made statements that demean law-abiding gun owners.”

“I am concerned that his confirmation would do significant damage to the collaborative working relationship that must exist between ATF, the firearms industry, sportsmen and women, and other law-abiding gun owners exercising their Second Amendment rights,” Collins said.

Let’s take a moment to review how we arrived at this point.

In April, President Biden nominated David Chipman to lead the ATF, and by all appearances, he’s a fine candidate: Chipman served as an ATF special agent for 25 years; he’s a respected policy expert; and he’s a veteran of the Justice Department. Chipman also recently worked as a senior policy adviser at former Rep. Gabby Giffords’ (D-Ariz.) organization — a group committed to reforming the nation’s gun laws.

If confirmed, he’d be the first Senate-confirmed ATF director since B. Todd Jones, a former federal prosecutor tapped for the job by then-President Barack Obama, who just barely passed Senate muster in 2015 — and who’s the only nominee to ever be confirmed. Senate Republicans didn’t even confirm Donald Trump’s nominee to lead ATF — and as a rule, GOP senators saw themselves as rubber stamps for whatever Trump wanted.

The trouble, of course, is that Republicans feared Trump’s nominee might strictly enforce the nation’s gun laws, and the party wasn’t prepared to let that happen. Indeed, one of the central reasons the ATF exists is to address gun trafficking and gun crimes, which has led GOP senators for a decade and a half to oppose practically every nominee to lead the agency.

Collins apparently intends to keep the streak alive, deeming Biden’s nominee as “unusually divisive,” after having used rhetoric gun owners found “demeaning.”

Obviously, senators can apply whatever standards they wish when evaluating executive-branch nominees, but the Maine Republican’s recent record is relevant. As regular readers may recall, Jeff Sessions’ attorney general nomination was divisive, but Collins helped confirm him anyway. Bill Barr was highly controversial, but the “centrist” senator voted to confirm him, too.

Mike Pompeo’s nomination was divisive, but he also picked up a “yes” vote from Collins. When Brett Kavanaugh’s Supreme Court nomination was pending, he was unusually aggressive in his partisan posture and was deeply divisive — only to be confirmed with Collins’ support.

And who can forget Richard Grenell, who was forced to delete hundreds of sexist comments from his social media accounts and who operated as a prominent online troll for far too long. Despite (or perhaps because of?) his obnoxious behavior on Twitter, Donald Trump nominated Ric Grenell for a diplomatic post. Care to guess which “moderate” senator voted to confirm him? If you said Collins, you’re correct.

The point, of course, is that Collins seemed to have little trouble voting for “unusually divisive” nominees in the Trump era, but under Biden, the Maine Republican has adopted a different set of standards.

Republicans won’t be able to derail the ATF nominee on their own, but it appears increasingly likely that Chipman will need unanimous support from Senate Democrats to be confirmed.