WASHINGTON (Reuters) - U.S. Attorney General Jeff Sessions fired the FBI’s former No. 2 official Andrew McCabe on Friday, prompting McCabe to say he was targeted for being a witness into whether President Donald Trump tried to obstruct the probe of Russian meddling in the 2016 election.

Sessions, in a statement on Friday, said he felt justified in firing McCabe after the Justice Department’s internal watchdog found he leaked information to reporters and misled investigators about his actions.

“The FBI expects every employee to adhere to the highest standards of honesty, integrity and accountability,” Sessions said.

But McCabe, who played a crucial role in the bureau’s investigations of Hillary Clinton and alleged Russian interference in the 2016 U.S. election, denied those claims and said he is facing retaliation by the Trump administration.

In a lengthy statement, McCabe said he believes he is being politically targeted because he corroborated former FBI Director James Comey’s claims that Trump tried to pressure Comey into killing the Russia probe.

McCabe kept detailed notes about his interactions with Trump, a source familiar with the matter said. Comey kept similar memos. Their notes and memos could become evidence in Special Counsel Robert Mueller’s probe into possible collusion between Moscow and Trump’s campaign.

Trump, who has denied any collusion, ousted Comey last year and acknowledged in a televised interview that he fired him over “this Russia thing.” Comey’s ouster paved the way for Deputy Attorney General Rod Rosenstein to tap Mueller to lead the probe.

McCabe’s dismissal came two days before his 50th birthday, when he would have been eligible to retire from the Federal Bureau of Investigation with his full pension. The firing - nine months after Trump fired Comey - puts the pension in jeopardy.

It also is likely to raise questions about whether McCabe received an overly harsh punishment due to political pressure by the Republican president, who had called for McCabe’s removal and blasted him on Twitter.

‘SINGLED OUT’

“I am being singled out and treated this way because of the role I played, the actions I took, and the events I witnessed in the aftermath of the firing of James Comey,” McCabe said in his statement.

“This attack on my credibility is one part of a larger effort ... to taint the FBI, law enforcement, and intelligence professionals more generally.”

In a message on Twitter, Trump praised McCabe’s firing and blasted both him and Comey.

Trump wrote: “Andrew McCabe FIRED, a great day for the hard working men and women of the FBI - A great day for Democracy. Sanctimonious James Comey was his boss and made McCabe look like a choirboy. He knew all about the lies and corruption going on at the highest levels of the FBI!”

McCabe had stepped down from his position as FBI deputy director in January but remained on leave pending retirement.

His departure was triggered by a critical report from the Justice Department’s inspector general that eventually led the FBI’s Office of Professional Responsibility to recommend he be fired.

The report, which has yet to be made public, says McCabe misled investigators about his communications with a former Wall Street Journal reporter who was writing about McCabe’s role in probes tied to Clinton, including an investigation of the Clinton family’s charitable foundation.

FILE PHOTO: Acting FBI Director Andrew McCabe testifies before a Senate Intelligence Committee hearing on Capitol Hill in Washington, D.C., U.S., June 7, 2017. REUTERS/Aaron P. Bernstein/File Photo

In his statement, McCabe denied misleading investigators.

He added that the release of the inspector general’s report was “accelerated” after he testified behind closed doors before the U.S. House Intelligence Committee where he revealed he could back up Comey’s claims.

POTENTIAL CRUCIAL WITNESS

Comey’s firing has become central to questions about whether Trump unlawfully sought to obstruct the Russia investigation.

McCabe could potentially be a crucial witness in Mueller’s investigation.

Trump and other Republicans have accused McCabe, a lifelong Republican who worked at the FBI for more than 20 years, of political bias and conflicts in connection with his oversight of investigations related to Clinton.

Some of that criticism stemmed from the fact his wife, Jill McCabe, a Democrat, received donations for her unsuccessful 2015 Virginia state senate campaign from Terry McAuliffe, who was the state’s governor at the time and an ally of the Clintons.

McCabe did not start overseeing the investigations until after his wife’s campaign ended, the FBI has said, and therefore did not have a conflict of interest.

On Twitter last year, Trump questioned why McCabe was allowed to oversee an investigation into Clinton’s use of a private email server while his wife received donations from “Clinton puppets.” He said McCabe was “racing the clock to retire with full benefits.”

Behind closed doors, Trump also asked McCabe who he voted for in the presidential election and referred to his wife as a loser, the same source familiar with the matter said.

McCabe initially did not respond to Trump’s question but later told Trump he did not vote in 2016.

Asked about this in January, Trump said he did not recall asking McCabe whom he voted for.

The inspector general’s report is largely focused on how McCabe answered questions about whether he leaked to the press in advance of a story that was critical of his oversight into the Clinton foundation investigation.

McCabe contends he did not view it as a leak but as an authorized disclosure commonplace in Washington between reporters and government officials.

He said he answered questions truthfully, and later, when he felt investigators misunderstood his answers, he tried to clarify his responses with them.