Washington (CNN) Nearly 20 years before William Barr heralded the end of the special counsel's probe of President Donald Trump , the attorney general laid out his complaints about special prosecutors: They have "no ultimate accountability," are unconstrained by resources and are often "driven to find something" to justify themselves.

"It's very easy for prosecutors to go hunting for scalps," Barr said in 2001.

Barr's comments that seemed to vindicate the President sparked an immediate backlash in Washington and turned Barr into a political lightning rod. While most Republicans have rallied to Barr, Democratic critics have blasted him for what they say is his mischaracterization of the report's findings.

However, a careful analysis of Barr's career and comments, as well as conversations with multiple people who have known and worked closely with him, reveal a veteran government and corporate lawyer who has always believed in the power of a strong presidency and in limiting the authority of career law enforcement officials.

A big problem, Barr said in 2001, is "this notion that has gained currency that there's something wrong about political officials reviewing cases. ... In fact, my attitude is -- and if these people only knew -- the second-guessing is not for political reasons, it's really because someone is exercising some maturity of judgment and putting things in perspective."

When his recent comments are seen through the lens of his full career, Barr's defense of Trump's potentially obstructive actions is entirely in keeping with who he's always been, going back to his first tenure as attorney general under President George H.W. Bush in the early 1990s. That history has some in Washington's legal community worried about a toxic combination.

"You have an attorney general with a maximal view of executive power and a President who has no sense of limits," said one former Justice Department official. "That's a recipe for constitutional calamity."

That tension boiled over this week ahead of Barr's scheduled testimony before the Senate and House Judiciary committees, with Barr threatening not to show up in front of the House panel on Thursday because of a dispute over the format, and where Democrats will surely press him on his decisions surrounding the release of special counsel Robert Mueller's report and his full vindication of the President. A new CNN-SSRS poll finds opinion on Barr's actions nearly evenly split , with 44% approve of Barr's handling of the special counsel's report and 43% disapprove. Beyond his handling of the report, 34% have a favorable opinion of Barr and 35% have an unfavorable opinion of him.

Yet even some critics of Barr say his decisions on the Mueller report are not "Trump-centric." Robert Bauer, the White House counsel for President Barack Obama, told CNN's Gloria Borger that Barr has held his views of expansive presidential power to influence the Justice Department's investigations "for decades."

"The criticism of Barr here, in my view, is not ... that he's acting as a defense lawyer of Donald Trump," Bauer said. "I do see he's helping Trump, for sure, but he's doing it because he's advancing a particular case that he feels very strongly about."

One piece of writing from Barr that has gotten attention recently is a 19-page memo he sent last year to Deputy Attorney General Rod Rosenstein, in which he argues that Trump's interactions with former FBI Director Comey should not constitute obstruction of justice. That memo is seen by some as Barr's attempt to get on Trump's radar and show his interest in becoming attorney general again. But some close to Barr say that's a misreading of the memo, and of Barr's motivations.

"If he wanted to audition to be attorney general, he would have gone on Fox News," a current Justice Department official told CNN. "Once you've been a successful attorney general and left with your reputation intact, you've won."

Same job, different department

Since being confirmed in February, Barr devoted a "significant" amount of time on the Mueller investigation and report during his first few months on the job, including nights and weekends, according to a Justice official. According to a source with knowledge, Barr has been preparing at length for back-to-back congressional hearings this week on the Russia investigation. Barr has been holed up with several senior officials in the Justice Department in his conference room for hours at a time since early last week, the source said, in addition to preparing on his own.

Barr has also been trying to get up to speed on what else is going on at the department, according to multiple sources there.

He's held numerous in-person meetings with US attorneys and the heads of each division. Barr has also extended an invitation to those in leadership positions to join him for lunch in the attorney general's dining room once a week. (Barr has also had a standing lunch date with his old friend and current White House counsel Pat Cipollone.)

Those around him at DOJ say Barr is determined to move on from Mueller's probe and refocus the department on priorities such as prosecuting hate crimes, enforcing immigration laws and protecting the integrity of the next election.

Barr has said he has no objections to Mueller testifying to Congress. Should that happen, congressional Democrats will almost certainly try to extract some sense of how Mueller feels about how Barr handled the report. That could provide some insight into the relationship between Barr and Mueller, both members of the close-knit world of Washington Republican lawyers.

The two have known each other at least since the 1980s when they both worked at the Justice Department, where Barr was deputy attorney general while Mueller was the assistant attorney general in charge of the department's criminal division. Their relationship extended beyond the office.

"I know they were close friends," C. Boyden Gray, the White House counsel under George H.W. Bush, told CNN. Their wives belong to a Bible study together, and the Barr and Mueller families have attended each other's social occasions, like their children's weddings. As he recounted during his January confirmation hearing, Barr told Trump in their first meeting in 2017 that "the Barrs and Muellers were good friends, and would be good friends when this is all over." That retelling reportedly caught the President off guard , and he complained to aides that he was unaware how close Mueller was to his pick for attorney general.

George Terwilliger, who served as Barr's deputy attorney general in the Bush administration and worked with Mueller as assistant US attorneys, confirmed the two men have a longstanding friendship. "I think it's probably more distant than when they used to see each other every day in the halls of the Justice Department, but I know of no reason to conclude it's not one of mutual respect," Terwilliger told CNN's Borger.

That respect does not obviate the two friends' stark disagreement about the special counsel's conclusions. Despite declining to reach a decision on obstruction, Mueller's detailed report provides volumes of evidence that Trump tried to interfere and even shut down the investigation.

But Barr's decision not to prosecute, in part, is based on the idea that without an underlying crime -- the President's involvement in a conspiracy with the Russians or some destruction of evidence, for example -- Trump would have been within his legal power to try to influence the investigation.

And in a recent appearance on Capitol Hill, Barr also hinted that the Justice Department may even pursue questions about the origins of the counterintelligence investigation into members of the Trump campaign. Barr told the Senate Appropriations Committee on April 10 that he believed "spying" by the FBI on the Trump campaign occurred in connection with the start of the probe. "I'm not suggesting that those rules were violated, but I think it's important to look at that," Barr said.

Later in the hearing Barr recharacterized his reference to "spying" as "surveillance," but sources close to the attorney general said that the bottom line is that he's addressing the issue now out of genuine concern, even if what's driving that concern is unclear.

A difference in legal opinion

Barr's concern about potential overreach by senior officials on the surveillance issue is in keeping with his long-held belief that career law enforcement officials require proper oversight, balanced by political accountability.

"I have come to feel that political supervision of the Department is very important. Politically responsible people. Someone ultimately has to answer to the political process," Barr declared in his 2001 interview with the Miller Center at UVA.

And this idea is at the heart of the attorney general's belief that the obstruction element of Mueller's investigation did not have much merit. This comes through in Barr's unsolicited June 2018 memo, which outlines an updated version of the skepticism about special counsel power he expressed back in 2001. Barr argues the President has broad power to influence investigations undertaken by the Justice Department, even those in which he is a target, particularly when there is no underlying crime.

"The Constitution," Barr wrote last year, "vests plenary authority over law enforcement proceedings in the President, and therefore one of the President's core constitutional authorities is precisely to make decisions 'influencing' proceedings." Barr argued that while there may be political constraints on a president's interference, there are no legal prohibitions.

"He alone is the Executive branch," Barr wrote of the president. "The determination whether the President is making decisions based on 'improper' motives or whether he is 'faithfully' discharging his responsibilities is left to the People, through the election process, and the Congress, through the Impeachment process"

It's the sort of narrow, legalistic view that prompts many of his friends and associates to label Barr a "lawyer's lawyer."

"I think Bill's view is a constitutional one. It's grounded in the separation of powers," said Terwilliger.

Democrats clearly disagree. Bauer said Barr should have stayed out of the decision on obstruction and left it to either Rosenstein or even accept Mueller's inability to reach a conclusion and not make a decision at all. "Let the Mueller report stand as it is presented in that report," Bauer told CNN. "It is at that point up to Congress to consider whether or not this is material or appropriate for consideration in an impeachment inquiry, and then another crew comes in at one point and makes the judgment after the President leaves office."

But defenders of Barr like Gray say it was Mueller's non-decision on obstruction that cut against norms. "The one thing that was different was Mueller's refusal to decide whether or not to prosecute, which is all a prosecutor's supposed to do," Gray told CNN.