Andrew McCabe, the deputy director of the FBI and longtime target of President Donald Trump’s ire, was fired by Attorney General Jeff Sessions on Friday. McCabe stepped down from his position in January amid weeks of Republican attacks but hadn’t planned to formally retire until March 18, his 50th birthday. Sessions’s decision to fire him ahead of that could strip him of his federal pension.

Justice Department Inspector General Michael Horowitz found that, in 2016, McCabe inappropriately allowed two top officials to talk to reporters about his decision to open a case into the Clinton Foundation. The inspector general determined that McCabe lied to investigators when asked about the matter, leaving it up to Sessions whether to fire him ahead of his retirement — which Sessions ultimately did.

“Pursuant to Department Order 1202, and based on the report of the Inspector General, the findings of the FBI Office of Professional Responsibility, and the recommendation of the Department’s senior career official, I have terminated the employment of Andrew McCabe effective immediately,” Sessions said in a statement.

McCabe responded with a fiery statement of his own. He said he was being “singled out and treated this way” because of what his actions after FBI Director James Comey was fired in May 2017 and that the attack on his credibility “is part of a larger effort not just to slander me personally, but to taint the FBI, law enforcement, and intelligence professionals more generally.” He said the “big picture” is a tale of what can happen when law enforcement is politicized.

President Donald Trump celebrated McCabe’s firing on Twitter.

Andrew McCabe FIRED, a great day for the hard working men and women of the FBI - A great day for Democracy. Sanctimonious James Comey was his boss and made McCabe look like a choirboy. He knew all about the lies and corruption going on at the highest levels of the FBI! — Donald J. Trump (@realDonaldTrump) March 17, 2018

The saga over McCabe — and President Trump’s animus toward him — goes back to a long-running controversy over McCabe’s wife’s allegedly compromising political ties to Hillary Clinton. In 2015, McCabe’s wife ran for a state Senate seat in Virginia, backed in part with money provided by the state Democratic party and a Clinton ally. Trump and other Republicans have used this probe to argue that McCabe is secretly harboring an anti-Republican agenda.

This came to a head in recent months, despite having been known for over a year, because McCabe’s name surfaced in a controversial text message sent by FBI agent Peter Strzok, who was recently removed from Special Counsel Robert Mueller’s Russia probe over evidence of anti-Trump political bias. Strzok had mentioned someone named “Andy” in a text message with federal attorney Lisa Page, seeming to suggest there was a discussion about Trump — and not a positive one — in McCabe’s office.

These revelations have led a number of prominent Republicans in Congress to outright call for McCabe’s firing.“He oughta be replaced. And I’ve said that before and I’ve said it to people who can do it,” Sen. Chuck Grassley (R-IA) told reporters in December.

But there is little evidence so far that McCabe harbors some kind of personal vendetta against the president, let alone any evidence that it’s affecting his job performance.

“He’s certainly not politically compromised — at least not based on what we now know,” Jens David Ohlin, a law professor at Cornell University, said. “It’s one thing for them to go after Mueller and his team — which I would expect — but the administration seems intent on delegitimizing the entire FBI and the Justice Department.”

This whole saga reflects an increasing Republican willingness to treat the FBI as an enemy of the party — a development with troubling implications for the bureau’s independence and the health of American democracy more broadly.

The long-running conservative case against McCabe

To understand the context for McCabe’s departure, we need to turn back the clock to 2015.

That year, Dr. Jill McCabe — Andrew’s wife — ran for Virginia state Senate with support of the state’s Democratic Party. She received $467,500 from then-Gov. Terry McAuliffe’s political action committee and $207,788 from the state’s Democratic Party. McAuliffe, it’s worth noting, is a political ally and personal friend of Bill and Hillary Clinton.

McCabe lost her campaign and didn’t run again. But the donations she received would turn out to be a big problem for her husband just a few months later, when they were revealed by Wall Street Journal reporter Devlin Barrett in October 2016. At the time, Deputy Director McCabe was overseeing the investigation into Hillary Clinton’s private email server — which just happened to be one of the biggest issues in the 2016 presidential election.

The Trump team screamed bias, and continued making noise about it even after his electoral victory. On January 12, the Justice Department’s Inspector General announced a probe into the FBI’s handling of the Clinton server investigation, including “allegations that the FBI Deputy Director should have been recused from participating in certain investigative matters.”

The probe’s findings have not yet been released but are at the basis of McCabe’s firing by Sessions. Thus far, there’s has been no indication that McCabe was compromised in anyway. The issue subsided for the early months of Trump’s presidency, sidelined by other controversies, until Trump fired FBI Director James Comey on May 9. This made McCabe acting FBI director; all of a sudden, a man that the president believed could be biased against him was in charge of (among other things) the probe into the Trump campaign’s connections to Russia.

It didn’t take too long for Trump to make his anger with this development known. On July 26, he called on Attorney General Sessions to fire McCabe. This level of presidential involvement in FBI personnel decisions is highly unusual, especially given the lack of concrete evidence of McCabe’s guilt:

Why didn't A.G. Sessions replace Acting FBI Director Andrew McCabe, a Comey friend who was in charge of Clinton investigation but got.... — Donald J. Trump (@realDonaldTrump) July 26, 2017

...big dollars ($700,000) for his wife's political run from Hillary Clinton and her representatives. Drain the Swamp! — Donald J. Trump (@realDonaldTrump) July 26, 2017

Sessions declined to do as Trump asked, and the issue died down once again — only to resurface in early December, when news of Strzok’s dismissal from the Mueller probe broke.

How the Strzok case turned McCabe into a target once again

The Justice Department released the text messages that got agent Strzok taken off the Mueller investigation in mid-December. The texts include some colorful descriptions of President Trump — Strzok referred to him as a “douche” and an “utter idiot,” among other things. He also said Clinton “just had to win” the race.

But one message, which Strzok sent in mid-2016 to US attorney Lisa Page, was more troubling. Here’s what it said:

I want to believe the path you threw out for consideration in Andy’s office — that there’s no way he gets elected — but I’m afraid we can’t take that risk. It’s like an insurance policy in the unlikely event you die before you’re 40.

It’s a really confusing message. “Andy” appears to be a reference to McCabe, which would make sense given that Strzok was working on the Clinton email case at the time. Many Republicans allege that the “insurance policy” line is evidence of some kind of plot against Trump on the part of the FBI, though the plain text of the message suggests nothing of the kind.

Because the message is so cryptic — we don’t even know for sure if “Andy” actually refers to McCabe, for instance — it’s hard to know what it’s actually referring to. But combined with the other texts openly critical of Trump and supportive of Clinton, it certainly suggested some degree of bias on Strzok’s part, and that’s evidently why Mueller chose to remove him from the investigation.

“’l’ll be a little bit surprised if he’s still an employee of the FBI this time next week”

But that wasn’t enough for some Republicans, who are convinced there is some deeper conspiracy afoot involving McCabe and are determined to get to the bottom of it. In January, members of the House Intelligence Committee grilled McCabe behind closed doors for more than seven hours.

And later that evening, House Judiciary Chair Bob Goodlatte (R-VA), and Gowdy, who chairs the House Oversight Committee, sent the Justice Department a letter announcing a joint investigation into the FBI’s handling of the Clinton email and Trump-Russia scandals. They requested that the bureau make McCabe available for yet another interview as part of that investigation.

Republican attacks on the FBI escalated again in January, when we learned that an unknown number of texts between two FBI employees between Strzok and Page had been deleted from FBI records. This turned out to be the result of an IT glitch, according to the best available evidence, but Republicans and their allies in the conservative press regularly accused the FBI of intentionally deleting them as part of a cover-up.

“Are we really supposed to believe that the FBI simply lost text messages from that important time frame? This is like Watergate but far worse,” Sean Hannity said in a monologue. “This reeks of law-breaking, it reeks of conspiracy, and it reeks of obstruction of justice.”

Independent experts like Ohlin, the Cornell professor, don’t see any strong ground to dismiss McCabe in any of this.

“I’d need a lot more evidence that his alleged bias involved any official acts,” says Andy Wright, a professor at Savannah Law School. “Based on the hearsay, unclear text ... or because his wife ran as a Democrat before Trump’s campaign? Please.”

And yet, he left the bureau and has now been fired.

Where does this all end?

We don’t know for sure that Republican pressure is the reason that McCabe left early for a fact. And McCabe isn’t the only one at the Justice Department that Republicans and the president have targeted.

A growing number of congressional GOP members and right-wing commentators are calling for Mueller himself to be dismissed for similar reasons: that is, his perceived bias against Trump. The evidence of such is similarly thin.

“Critics of [Mueller] point to what they call a mound of evidence — much of it exaggerated, mischaracterized, or outright false — to justify his potential ouster,” writes Vox’s Alex Ward.

A number of observers see these efforts are part of a broader GOP ploy to paint the DOJ as hopelessly biased against Trump and thus soften the blow of any potential charges against the president or his associates that come out of the Mueller probe.

“Usually the GOP is a law-and-order party, very pro-police,” Ohlin says. “But they seem to be on the verge of declaring war on the country’s top law enforcement agency.”

Trump already fired FBI director James Comey back in May, raising questions about whether the president was trying to thwart the FBI’s investigation into his campaign’s ties with Russia. In that context, McCabe’s early retirement and subsequent firing so that he’ll be without his pension after years of service sends a chilling message: Draw the president’s ire, especially by investigating him, and watch out.