Johnson says he understands White House reason for firing IG but Pelosi says Congress hasn't received any more justification

But Johnson declined to elaborate on the justification given for Linick's ouster during an interview with CNN's Jake Tapper on "State of the Union," and Democratic leadership swiftly denied that the Trump administration had provided them any additional reason for the watchdog's removal beyond President Donald Trump's Friday announcement.

Johnson, the Republican chairman of the Homeland Security Committee, told Tapper that he "spoke with senior officials both in the White House and the State Department" and that he understands the reasoning. "I don't know whether they're going to provide any more robust rationale for doing it," he said.

But on CBS' "Face the Nation," House Speaker Nancy Pelosi said she hadn't received any additional reasoning.

"This is new to us and typical of the White House -- announcing something that is very unsavory, they would do it late on a Friday night," Pelosi said.

"Even Republicans in Congress are concerned," she said.

Trump on Friday fired Linick, the latest in a series of dismissals of independent government watchdogs that have come in the wake of the President's acquittal on articles of impeachment earlier this year. The removal came in yet another late-night firing of an inspector general -- a dismissal that drew immediate condemnation from top Democrats, who accused the President of engaging in a pattern of retaliation against public servants charged with oversight of his administration, and some criticism from outspoken members of the President's own party.

Johnson on Sunday suggested the inspector general had been stonewalling the Senate on an investigation he declined to name.

"Both Sen. (Chuck) Grassley and I had a real problem with his responsiveness to, in particular, one oversight request," he said.

Grassley, an Iowa Republican and a longtime proponent of inspectors general, issued a statement on the firing on Saturday, saying, "As I've said before, Congress requires written reasons justifying an IG's removal. A general lack of confidence simply is not sufficient detail to satisfy Congress."

He told CNN's Manu Raju on May 4 he did not think more legislation was necessary to protect IGs, saying: "I think we have plenty of laws to protect inspectors general."

Pelosi on Sunday acknowledged that Trump does have the legal authority to remove inspectors general, but suggested the circumstances of the removal matter.

"The President has a right to fire any federal employee, but the fact is if it looks like it's in retaliation ... that could be unlawful," she said.

Pelosi also did not say she had direct knowledge of the investigation Linick had opened into Secretary of State Mike Pompeo.

"I trust the word of my chairman," she said. "I only got this letter from the President that night, but he didn't say in that letter any reason except that he lost confidence."

Not long after Linick's firing was announced, House Foreign Affairs Committee Chairman Eliot Engel said Linick had opened an investigation into Pompeo.

"I have learned that the Office of the Inspector General had opened an investigation into Secretary Pompeo," Engel, a Democrat, said in his statement denouncing the firing. Engel did not provide any further details about the scope of this investigation or how he learned about it.

A State Department source confirmed to CNN on Saturday that there is an investigation into the alleged improper use by Pompeo of a political appointee, but the source was unsure when the investigation began.

Sarah Breen, the State Department's Office of Inspector General director of communications, told CNN in an email, "We cannot confirm or deny the existence of any specific investigation."

The inspector general investigation Engel referenced centers around possible misuse of a political appointee at the State Department to perform personal tasks for Pompeo and his wife, a Democratic congressional aide with knowledge of the investigation told CNN.

A source close to Linick told CNN the allegation raised by the Democratic aide had previously been brought to Linick's office but was not aware of an official investigation being opened into the matter.

A senior State Department official confirmed that Pompeo made the recommendation that Linick be removed, but the official did not know the reasons why.

Trump said the dismissal was based on a lack of confidence in Linick. CNN has previously reported that the President has long been fixated on ridding his administration of government watchdogs he views as Obama loyalists and now appears to be working toward achieving that goal.

This story has been updated with comments from House Speaker Nancy Pelosi.