President-elect Donald Trump’s stunning announcement on Saturday night that he will nominate Kash Patel as FBI director sets the stage for a fresh round of turbulence at a law enforcement agency tasked with protecting the homeland and investigating federal crimes.

Patel, a steadfast Trump ally with plans to shake up the institution he’s been tapped to lead, is a study in contrasts from the current tight-lipped director who preaches a “keep calm and tackle hard” mantra.

In selecting Patel over more conventional contenders, Trump is again testing his ability to get the Senate to bend to his will by confirming some of his more provocative nominees.

What happens to the current FBI director?

Christopher Wray was appointed director by Trump in 2017 and technically has three years left on his 10-year tenure.

That length of time is meant to ensure that directors of the nation’s most prominent federal law enforcement agency can operate free from political influence or pressure. Presidents have typically but not always retained the director who was in place at the time they took office, as President Joe Biden has done with Wray.

But it’s also the case that all FBI directors serve at the pleasure of the president; indeed, Wray was nominated after Trump fired the FBI chief he’d inherited when he took office, James Comey.

The announcement means that Wray can either resign from the job, consistent with Trump’s apparent wishes, or wait to be fired once Trump takes office in January. Either way, the selection of a successor is a clear indication that Wray’s days are numbered. Should Wray leave before Patel can be confirmed, the position of acting director would presumably be filled in the interim by the FBI’s current deputy director.

Can Patel be confirmed by the Senate?

Republicans may have won control of the Senate, but his confirmation is not assured.

There are no doubt lawmakers who support Trump’s desire for a radically overhauled FBI, particularly following federal investigations that resulted in two separate indictments against the president-elect, and who share his sentiment that federal law enforcement has been “weaponized” against conservatives.

But Patel is likely to face deep skepticism during his confirmation hearings over his stated plans to rid the government of “conspirators” against Trump, and his claims that he would shut down the FBI’s Pennsylvania Avenue headquarters in the nation’s capital and send the thousands of employees who work there to “chase down criminals” across the country.

And while Trump may have wanted a loyalist willing to pursue retribution against his perceived adversaries, that perspective is likely to give pause to senators who believe that the FBI and Justice Department should operate free of political influence and not be tasked with carrying out a president’s personal agenda.

Foreshadowing the potentially bruising confirmation fight ahead, Sen. Chris Coons, a Delaware Democrat, wrote on social media late Saturday: “Kash Patel will be another test of the Senate’s power of advice and consent. Patel needs to prove to the Senate Judiciary Committee that he has the right qualifications and, despite his past statements, will put our nation’s public safety over a political agenda focused on retribution.”

Trump has also raised the prospect of using recess appointments to push his nominees through the Senate.

If Patel is confirmed, can he actually do what he’s said he’ll do?

Patel has made a series of brash claims about his plans for the federal government, but most of those proposals would require backing and buy-in from other officials and would almost certainly encounter significant resistance. His claim that he would reduce the FBI’s footprint and authority stands in contrast to the tack traditionally taken by leaders of the bureau, who invariably say they want more resources — not less.

He’s talked about trying to rid the government of “conspirators” against Trump and of going “after the people in the media who lied about American citizens who helped Joe Biden rig presidential elections,” whether criminally or civilly.

Under the FBI’s own guidelines, criminal investigations can’t be rooted in arbitrary or groundless speculation but instead must have an authorized purpose to detect or interrupt criminal activity. And while the FBI conducts investigations, the responsibility of filing federal charges, or bringing a lawsuit on behalf of the federal government, falls to the Justice Department. Trump last week said he intended to nominate former Florida attorney general Pam Bondi to serve as attorney general.

Patel’s proposed crackdown on leaks of information by government officials to the media is an indication that he wants the Justice Department to undo its current policy prohibiting the secret seizure of reporters’ phone records in leak investigations. That policy was implemented by Attorney General Merrick Garland following an uproar over the revelation that federal prosecutors had obtained subpoenas for journalists’ phone records.

Patel has talked about disentangling the FBI’s intelligence-gathering operations — now a core function of the bureau’s mandate — from the rest of its operations. It’s unclear whether he intends to carry through on that pledge or how it would be greeted at a time when the U.S. is facing what officials say is a heightened threat of terrorism.

He also says he wants to close down the FBI’s storied Pennsylvania Avenue headquarters and send the employees who work there across the country. It’s not clear if that’s a hyperbolic claim simply reflecting disdain for the “deep state” or something he’d actually try to implement, but how that would look in practice remains a big question mark.