President Trump’s latest outburst against Attorney General Jeff Sessions – escalating a year-long public flogging of the mild-mannered former senator – is raising the question: How much longer will Sessions endure?

Trump tore into his top law enforcement official on Tuesday over his decision to ask the inspector general to review alleged surveillance abuse by intelligence agencies. Trump complained that the IG is an “Obama guy” and such an investigation will “take forever” (though the inspector general has served under presidents of both parties).

"Why not use Justice Department lawyers? DISGRACEFUL!" Trump tweeted.

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Sessions typically does not respond to the president's periodic swipes -- but this one drew a rare, if measured, retort.

"We have initiated the appropriate process that will ensure complaints against this Department will be fully and fairly acted upon if necessary," he said in a statement. "As long as I am the Attorney General, I will continue to discharge my duties with integrity and honor, and this Department will continue to do its work in a fair and impartial manner according to the law and Constitution."

Those who know Sessions sounded off Wednesday about his predicament. Alabama Sen. Richard Selby, Sessions’ former colleague, pointedly said he wouldn’t stay if he were in Sessions’ shoes.

"I wouldn't be anybody's whipping boy,” he said on Fox Business Network’s “Cavuto.” “I wouldn't be belittled because the president is saying you don’t have any confidence in me."

Shelby called Sessions a “good man.”

"He's going through a lot. He has a lot of challenges," he said.

Former Attorney General Michael Mukasey backed Sessions’ decision to ask the IG to investigate FISA abuse, calling the move “precisely the right choice.”

“If anyone at DOJ should look into the circumstances of this FISA application, it is the IG, who reports to both the Attorney General and Congress,” he said in a statement.

Trump’s attack was the latest in a long line of public swipes at the AG, who was one of Trump’s earliest supporters and is otherwise aligned with Trump's base on issues like immigration and crime.

But their relationship soured within months of Trump taking office, largely over Sessions’ decision to recuse himself from the Russia meddling investigation.

According to one published account, Sessions tried to resign last May after Trump called him an "idiot," but then-Chief of Staff Reince Priebus intervened and helped convince him to stay.

The jabs have continued since then. Last week, Trump told Twitter followers to "ask Jeff Sessions" about why the Obama administration was not under investigation for its failure to stop Russian interference.

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TRUMP SLAMS SESSIONS FOR USING 'OBAMA GUY' TO INVESTIGATE 'MASSIVE FISA ABUSE'

The Washington Post reported Wednesday that Trump now refers to Sessions as “Mr. Magoo” -- the bumbling elderly cartoon character.

Sessions, however, has persisted.

His staff marked the anniversary of his confirmation by buying him a bulletproof vest with his name on it as a gift, the Post reports. There is no indication right now that Sessions plans to step down, and Axios reports that Sessions dined Wednesday at a high-end D.C. restaurant with deputy Rod Rosenstein and Solicitor General Noel Francisco in what it described as a show of solidarity.

However, the outlet also described Sessions’ allies as “deeply concerned” by the latest feud, noting that it feels "different" from previous displays.

If the attorney general chooses to stay, it would seem unlikely Trump would look to fire him outright, especially given the chaos that followed the ouster of FBI boss James Comey.

Doing so could fire up the already-piqued interest of FBI Special Counsel Robert Mueller, who the Post reports is already investigating a period last summer where Trump tried to push Sessions out, amid concerns Trump was looking to replace him with someone who would exercise control over the Russia probe.

Fox News’ Catherine Herridge contributed to this report.