WASHINGTON — Sen. Susan Collins of Maine slammed former FBI Director James Comey on Sunday for releasing his memoir during the ongoing Russia probe, saying she worries the book could interfere with the investigations.

"I cannot imagine why an FBI director would seek to essentially cash in on a book when the investigation is very much alive," she said on NBC's "Meet the Press." "He should have waited to do his memoir."

Collins, a member of the Senate’s Select Committee on Intelligence, which is conducting its own investigation into Russian interference in the 2016 election in addition to the Department of Justice probe run by special counsel Robert Mueller, also said that if she were advising a future FBI director, she would tell that person two things.

"One, always follow the Department of Justice’s protocols and guidelines, which unfortunately James Comey did not do with the Hillary Clinton investigation and he did not do when he leaked documents that were FBI work documents to a friend of his, knowing that they would go to the press,” she said. "And, so that would be my first advice. The second would be don’t write a book in the middle of an investigation.”

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Comey, who was fired by President Donald Trump last May, has attempted to pitch himself as above the political fray but has again come under scrutiny from both Democrats and Republicans since re-emerging on the public stage.

He has staunchly defended his choices to make public announcements regarding the Clinton email investigation, both after its initial conclusion in July 2016 and again when new information was found in late October 2016, as necessary to maintain public confidence that the investigation was being conducted fairly.

Comey has said the information from his memos about Trump that he later gave to a friend, who subsequently gave to media outlets, was not classified. Comey told the Senate Intelligence Committee last year that he wanted to make some of the contents public because he "thought that might prompt the appointment of a special counsel."

Collins on Sunday also said that she believes it’s important for members of Congress to “have a debate” on legislation that’s aimed at protecting a special counsel like Mueller from termination by the president, despite the fact that Senate Majority Leader Mitch McConnell has said such a bill would not make it to a vote on the floor.

The debate is important, she said, “in order to send a clear message to the president that Congress does not support his taking any action with regard to Mr. Mueller’s investigation.”

Though Collins added that she doesn’t believe Trump would ever sign such a bill, and might even veto a larger one if similar provisions were attached.

White House Legislative Affairs Director Marc Short, also on Sunday’s “Meet the Press,” was adamant that the president does not have any plans to fire Mueller, but left some room open for the possibility.

“You don’t know how far off this investigation is going to veer,” he said. "Right now, he has no intention of firing him.”

Collins, however, said she believes Mueller is staying "within the parameters" of the investigation.

The Maine Republican also said Sunday she plans to vote to confirm Mike Pompeo as secretary of state, but hasn’t yet decided whether she will support Gina Haspel to replace him as CIA director, saying she wants to wait until Haspel appears at a hearing before the Senate Intelligence Committee next month.

“We still have a lot of questions to ask of her,” Collins said.