Attorney General Jeff Sessions resigned on Wednesday, the latest in a growing list of prominent administration departures.

Why it matters: Sessions' exit came after months of public criticism from his boss. Such attacks on his own Cabinet members, especially when it was explicitly in reaction to Robert Mueller's Russia probe, was not normal.

Be smart: Trump often talked about replacing current staff members, as Axios' Jonathan Swan has reported, but he didn't always follow through.

Timeline: From February 2016 until June 2017, President Trump praised Sessions as "a world-class legal mind and considered a truly great Attorney General and US Attorney in the state of Alabama."

He even emailed the Washington Post at the start of 2017 saying that Sessions is “a truly fine person” who is "so highly respected by everyone."

And then things changed:

July 19, 2017: "Sessions should have never recused himself, and if he was going to recuse himself, he should have told me before he took the job and I would have picked somebody else."

"Sessions should have never recused himself, and if he was going to recuse himself, he should have told me before he took the job and I would have picked somebody else." July 24, 2017: "So why aren't the Committees and investigators, and of course our beleaguered A.G., looking into Crooked Hillarys crimes & Russia relations?"

"So why aren't the Committees and investigators, and of course our beleaguered A.G., looking into Crooked Hillarys crimes & Russia relations?" Axios broke the news that Trump was considering bringing back Rudy Giuliani as attorney general.

July 25, 2017: Axios reports Trump called a longtime political associate and asked out of the blue: "What would happen if I fired Sessions?"

Axios reports Trump called a longtime political associate and asked out of the blue: "What would happen if I fired Sessions?" July 26, 2017: Trump tweets asking why Sessions didn't fire acting FBI Director Andrew McCabe.

Trump tweets asking why Sessions didn't fire acting FBI Director Andrew McCabe. Feb. 21, 2018: Days after Mueller indicted 13 Russian nationals and three Russian entities for violating criminal law to interfere with the 2016 U.S. election, Trump tweets: "If all of the Russian meddling took place during the Obama Administration, right up to January 20th, why aren’t they the subject of the investigation? Why didn’t Obama do something about the meddling? Why aren’t Dem crimes under investigation? Ask Jeff Sessions!"

Days after Mueller indicted 13 Russian nationals and three Russian entities for violating criminal law to interfere with the 2016 U.S. election, Trump tweets: "If all of the Russian meddling took place during the Obama Administration, right up to January 20th, why aren’t they the subject of the investigation? Why didn’t Obama do something about the meddling? Why aren’t Dem crimes under investigation? Ask Jeff Sessions!" Feb. 28, 2018: The Republican memo was released on Feb. 2, which alleged the DOJ and FBI's mishandling of FISA applications and surveillance. "Why is A.G. Jeff Sessions asking the Inspector General to investigate potentially massive FISA abuse. Will take forever, has no prosecutorial power and already late with reports on Comey etc. Isn’t the I.G. an Obama guy? Why not use Justice Department lawyers? DISGRACEFUL!"

The Republican memo was released on Feb. 2, which alleged the DOJ and FBI's mishandling of FISA applications and surveillance. "Why is A.G. Jeff Sessions asking the Inspector General to investigate potentially massive FISA abuse. Will take forever, has no prosecutorial power and already late with reports on Comey etc. Isn’t the I.G. an Obama guy? Why not use Justice Department lawyers? DISGRACEFUL!" May 30, 2018: “The recusal of Jeff Sessions was an unforced betrayal of the President of the United States.” JOE DIGENOVA, former U.S. Attorney.

“The recusal of Jeff Sessions was an unforced betrayal of the President of the United States.” JOE DIGENOVA, former U.S. Attorney. June 5, 2018: "The Russian Witch Hunt Hoax continues, all because Jeff Sessions didn’t tell me he was going to recuse himself...I would have quickly picked someone else. So much time and money wasted, so many lives ruined...and Sessions knew better than most that there was No Collusion!"

"The Russian Witch Hunt Hoax continues, all because Jeff Sessions didn’t tell me he was going to recuse himself...I would have quickly picked someone else. So much time and money wasted, so many lives ruined...and Sessions knew better than most that there was No Collusion!" In August, Trump questioned whether or not the Department of Justice under Sessions was truly just, calling it "A total joke!"

Trump questioned whether or not the Department of Justice under Sessions was truly just, calling it "A total joke!" Nov. 7, 2018: Sessions resigned.

Don't forget: Sessions was one of Trump's earliest supporters during the campaign (endorsing him in February 2016). He has stood by Trump's side ever since, often moving forward on many of Trump's most controversial policy proposals, like the travel ban, stricter drug sentencing, immigration, and cracking down on administrative leaks.

Go deeper: See how Mueller's timeline aligns with Trump's evolving mood on Sessions.