Former Acting FBI Director Andrew McCabe said the possibility of an "inappropriate relationship" between President Trump and the government of Russia prompted his decision to launch obstruction of justice and counterintelligence investigations into the president.

In a clip that aired on "Face the Nation" from McCabe's "60 Minutes" interview, McCabe told correspondent Scott Pelley he launched the investigations shortly after speaking with Mr. Trump on details surrounding the dramatic 2017 firing of McCabe's own boss, former FBI Director James Comey.

"It's many of those same concerns that caused us to be concerned about a national security threat. And the idea is, if the president committed obstruction of justice, fired the director of the FBI to negatively impact or to shut down our investigation of Russia's malign activity and possibly in support of his campaign, as a counterintelligence investigator you have to ask yourself, 'Why would a president of the United States do that?'" McCabe said.

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He added, "So all those same sorts of facts cause us to wonder, is there an inappropriate relationship, a connection between this president and our most fearsome enemy, the government of Russia?"

In the interview, which will air Sunday on "60 Minutes," McCabe told Pelley he briefly discussed the 25th Amendment with then-Deputy Attorney General Rod Rosenstein. McCabe said Rosenstein "raised the issue and discussed it with me in the context of thinking about how many other cabinet officials might support such an effort."

McCabe's spokesperson, Melissa Schwartz, said in a statement Friday to CBS News' Paula Reid that "at no time did Mr. McCabe participate in any extended discussions about the use of the 25th Amendment, nor is he aware of any such discussions."