Attorney General William P. Barr testifies before the Senate Judiciary Committee this month. (Jahi Chikwendiu/The Washington Post)

Attorney General William P. Barr is on something of a media tour. In his first interviews since taking control of the Justice Department, he has expounded upon and defended some of his controversial decisions.

In an interview with the Wall Street Journal’s Sadie Gurman, he said something revealing too:

... Mr. Barr, who as a private citizen bristled at the barrage of legal and other challenges Mr. Trump faced during his first two years in office, said his long-held belief in executive power is more about protecting the presidency than the current officeholder.

“I felt the rules were being changed to hurt Trump, and I thought it was damaging for the presidency over the long haul,” Mr. Barr said.

That sentiment plus coaxing from friends led the 68-year-old grandfather of five to sign on for another turn at the helm of the Justice Department, where his quest to protect presidential power has taken on new significance in light of special counsel Robert Mueller’s report and the Trump administration’s effort to thwart congressional oversight.

That is the attorney general of the United States saying he decided to take his job because he has an agenda he wants to satisfy. Imagine if he had said during his confirmation hearing that he wanted the job to protect President Trump’s powers.

The Post’s Tom Hamburger did yeoman’s work last week laying out how long Barr has subscribed to an expansive view of executive authority. This has been evident since the last time he joined the Justice Department in 1989. His Democratic successor as the head of the Justice Department’s Office of Legal Counsel, Walter Dellinger, told my colleague that "there is nobody who is to his right on this issue.”

So it’s hardly surprising that Barr believes in this. But believing in it is different from saying you took the job to further a specific goal. Imagine if Barack Obama had picked Eric Holder to lead the Justice Department, and Holder came out and said he wanted to be attorney general to protect Obama’s prerogatives — not because of Obama, mind you, but because of the presidency. Imagine if George W. Bush picked Alberto Gonzales, and Gonzales soon declared that he wanted the job because he felt there was too much scrutiny of Bush’s war powers, and he wanted to set things straight.

Barr seems to believe his quest is just and apolitical because it’s not about Donald Trump, but rather protecting the presidency as an institution. But it’s going to be pretty difficult to not measure his decisions against the outcome he set out to achieve. Whenever there is a judgment call involving presidential powers, what is Barr going to do if he believes the presidency as an institution is under assault from the meddling legislative branch? He’s going to err on the side of the presidency — and therefore, of Trump.

The writing was on the wall for all of this. Barr wrote that long memo decrying special counsel Robert S. Mueller III’s obstruction of justice probe. He said there was more evidence to investigate conspiracy theories involving the Clintons than there was to investigate potential Trump campaign collusion with Russia. He said Trump had "made the right call” by firing FBI Director James B. Comey.

But to come out and say you came to Washington to protect the presidency in your role as the nation’s top law enforcement official — rather than simply to enforce the law — is quite a bold statement.