WASHINGTON (AP) — Steve Linick irritated powerful Democrats and Republicans alike in his seven years as the independent watchdog investigating waste and mismanagement at the State Department. Still, he was stunned by a Friday night phone call saying President Donald Trump had fired him.

Linick's access to the computer system, and to the building, was cut off. He asked for a reason, and none was given. He could only surmise his dismissal as inspector general was tied to him investigating Secretary of State Mike Pompeo, according to a person familiar with his account, who spoke on the condition of anonymity to discuss a private conversation.

Linick's dismissal was part of a wave of firings or demotions by Trump that, even for a president with a "you're fired" catchphrase, has been notably brazen for their appearance of retribution and vindictiveness. Trump's moves, coming with Washington consumed by the coronavirus, have upended the longstanding bipartisan support for officials tasked with ensuring the integrity of government agencies — and roiled a watchdog community whose work presidents may not always like but learn to tolerate.

"There's a tension between what his instincts are, which is to brook no criticism whatsoever, and what the inspector general's job is as defined by statute, which is to do independent audits and investigations," said former Justice Department inspector general Michael Bromwich.

Trump's actions, done with minimal explanation, have triggered congressional demands for answers, with House investigators scheduled to interview Linick on Wednesday. Linick plans to tell them that he has "served without regard to politics" in his nearly three-decade career in public service and has always been committed to independent oversight, according to opening remarks obtained by The Associated Press.

Trump has made clear at least some of the moves were personal.

He said he fired the intelligence community watchdog, Michael Atkinson, in April because he had alerted Congress to the whistleblower report on Ukraine that Democrats used for his impeachment. He raged that Atkinson was insufficiently loyal and part of the "Deep State" that has opposed his presidency from the beginning, according to three current or former administration officials. Trump had wanted to fire Atkinson weeks earlier, only to be talked out of it by his advisers, they said.

After he fired Linick last month, he labeled him an Obama appointee and said he'd acted on the encouragement of Pompeo, who denied it was retaliation but said he wished he'd recommended it sooner.

In between, Trump selected a replacement for Christi Grimm of Health and Human Services after she issued a report that the president openly scorned. He demoted Glenn Fine as acting Defense Department watchdog, stripping him of oversight of the $2 trillion coronavirus relief effort. Democrats have raised questions about whether a Transportation Department acting inspector general who was removed was replaced for political reasons, too.

All presidents take umbrage at inspector general oversight, a post-Watergate concept meant to root out waste, fraud and corruption. Armed with teams of investigators and broad powers, the more than 70 inspectors general are often a thorn for their agencies, documenting profligate spending, mismanagement and other concerns — CIA interrogation of terror suspects, for instance — that can make front-page news.

President Ronald Reagan fired incumbent inspectors general after taking office, though he reappointed some. President Barack Obama dismissed one early in his tenure with minimal explanation.

"Trump has been more transparent in his opposition, and he's been more willing to take very aggressive actions, but this is an institution created by Congress and protected by Congress — and presidents just don't like it," said New York University public service professor Paul Light.

Chuck McCullough, the intelligence community inspector general under Obama, said he maintained a sparsely decorated office, aware he could be fired any time. McCullough and Linick were instrumental in raising concerns former Secretary of State Hillary Clinton may have mishandled classified information on a private email server. McCullough said he was told during the 2016 election by a Clinton associate that, in a Clinton presidency, he and Linick would be the "first to be fired."

Congressional Democrats say Linick was fired while investigating how the State Department pushed through a $7 billion Saudi arms sale over congressional objections. He was also reviewing how Pompeo treated certain staff.

Pompeo has said he knew about the Saudi investigation. But he denied Linick's dismissal was retaliatory, suggesting instead Linick wasn't on board with the department's mission.

In a letter to lawmakers obtained Wednesday, Under Secretary of State Brian Bulatao wrote that "concern over Linick had grown" about his handling of what the State Department says was the unauthorized disclosure of a draft inspector general report and potential misconduct within the inspector general office.

In other administrations, investigating a Cabinet secretary might be insurance against being fired because the optics of doing so would be damaging. Not so for Trump.

"With Trump, it just kind of lays bare all the old sort of bluffing about how IGs are protected," McCullough said.

But Trump has appeared flummoxed by the inability to control watchdogs, as evidenced by his anger at Atkinson over the whistleblower complaint that documented his efforts to get Ukraine to dig up dirt on Democratic rival Joe Biden.

Though presidents' ability to fire inspectors general is well-established, Congress is raising questions about the dubious qualifications of some of the replacements and, in some cases, their apparent conflicts.

Trump, for instance, has selected a policy adviser at Customs and Border Protection to replace the deeply experienced Fine, who had been acting inspector general at the Pentagon for four years and Justice Department watchdog for a decade before that.

Senior officials at the State and Transportation departments are functioning as acting inspectors general at their agencies, effectively holding two jobs at once and setting up a conflict that good-government advocates and some in Congress say is untenable.

McCullough, now a partner at the Compass Rose Legal Group, said he doubted Trump's moves would stymie investigations by career employees, but said the climate nonetheless complicates recruitment of "the best and the brightest."

"And if you do recruit people under this sort of climate," he asked, "are their findings going to be as aggressive and hard-hitting and as factual as everyone expects?"