Former FBI Deputy Director Andrew McCabe feared that he might be ousted before the obstruction of justice and counterintelligence investigations into President Donald Trump's Russia ties — which McCabe says he authorized — were "on absolutely solid ground."

McCabe, who ultimately was fired by then-Attorney General Jeff Sessions on the eve of his retirement last year, made the remarks in a CBS interview that aired in part Thursday.

He said that he launched the probes a day after speaking with Trump in May 2017, in a conversation following the firing of former FBI Director James Comey.

"I was very concerned that I was able to put the Russia case on absolutely solid ground, in an indelible fashion," McCabe said in the interview. "That were I removed quickly, or reassigned or fired, that the case could not be closed or vanish in the night without a trace."

Trump, his legal team and the White House have consistently denied any wrongdoing involving Russia.

In a statement Thursday afternoon, White House press secretary Sarah Sanders said McCabe "was fired in total disgrace from the FBI because he lied to investigators on multiple occasions, including under oath. His selfish and destructive agenda drove him to open a completely baseless investigation into the President. His actions were so shameful that he was referred to federal prosecutors. Andrew McCabe has no credibility and is an embarrassment to the men and women of the FBI and our great country."

Trump, who has excoriated McCabe on Twitter dozens of times, also pushed back Thursday on the ex-FBI official's account.

"Disgraced FBI Acting Director Andrew McCabe pretends to be a 'poor little Angel' when in fact he was a big part of the Crooked Hillary Scandal & the Russia Hoax," Trump said in a tweet.

The president also referenced a report from the Justice Department's inspector general, which concluded that McCabe inappropriately leaked information to a reporter and then misled investigators about it. "I.G. report on McCabe was devastating. Part of 'insurance policy' in case I won," Trump said.

Trump TWEET Disgraced FBI Acting Director Andrew McCabe pretends to be a "poor little Angel" when in fact he was a big part of the Crooked Hillary Scandal & the Russia Hoax - a puppet for Leakin' James Comey. I.G. report on McCabe was devastating. Part of "insurance policy" in case I won....

Trump TWEET ....Many of the top FBI brass were fired, forced to leave, or left. McCabe's wife received BIG DOLLARS from Clinton people for her campaign - he gave Hillary a pass. McCabe is a disgrace to the FBI and a disgrace to our Country. MAKE AMERICA GREAT AGAIN!

Trump cited guidance from Deputy Attorney General Rod Rosenstein when he fired Comey. McCabe reportedly claims in his upcoming book, "The Threat: How the FBI Protects America in the Age of Terror and Trump," that Rosenstein wrote the memo against his wishes and under order from Trump.

"He said it wasn't his idea. The president had ordered him to write the memo justifying the firing," McCabe recalled Rosenstein saying at a May 2017 meeting, The Guardian first reported.

Eight days after Comey's firing, special counsel Robert Mueller was appointed to carry out the investigation into Russia's interference in the 2016 election. His ongoing probe has collected indictments or guilty pleas from 34 people and three companies, which include Trump's former campaign chief Paul Manafort, former campaign aide George Papadopoulos, former national security advisor Michael Flynn and a raft of Russian nationals.

McCabe said in the CBS interview that he was deeply concerned about the possibility that Russia helped Trump win the presidential election.

"I was speaking to the man who had just run for the presidency and who had just won the presidency, and who might have done so with the aid of the government of Russia, our most formidable adversary on the world stage," McCabe said. "And that was something that troubled me greatly."

Asked how long after that conversation he started the probes involving Trump, McCabe said: "I think the next day, I met with the team investigating the Russia cases, and I asked the team to go back and conduct an assessment to determine where are we with these efforts and what steps do we need to take going forward."

He added that "I wanted to make sure that our case was on solid ground, and if somebody came in behind me and closed it and tried to walk away from it, they would not be able to do that without creating a record of why they'd made that decision."