Following President Donald Trump's firing of FBI Director James Comey, critics have called the move "Nixonian" and compared it to the Watergate scandal that brought down the administration of former President Richard Nixon.

In October 1973, Nixon demanded the resignations of Attorney General Elliot Richardson and his deputy William Ruckelshaus when they refused to fire special prosecutor Archibald Cox, who was looking into Watergate.

Pat Buchanan, a Nixon speechwriter and adviser, said on "The Fox News Specialists" the two situations are not comparable, because of the circumstances surrounding Watergate and the Saturday Night Massacre, as Nixon's firings were dubbed.

He explained the firings occurred the week after Vice President Spiro Agnew resigned, while the Yom Kippur War was raging and Israel was in "desperate straits," and while the U.S. was in nuclear negotiations with Russia.

Cox backed out of a deal regarding documents he would be given related to the Watergate investigation, and Nixon told Richardson and Ruckelshaus that Cox had to be fired. When they refused, the next step was obvious, Buchanan said.

"Nixon had to fire his [attorney general], and I recommended it," Buchanan said, adding that Nixon "had no other choice" than to fire a cabinet member who refused an order during such trying times.

He also said he knew the Watergate scandal would lead to Nixon being impeached, because there was evidence of a real crime, something he doesn't see with the allegations surrounding the Trump campaign colluding with Russia.

Buchanan said he believes Trump became "exasperated" with Comey leading a months-long investigation into his campaign, with no evidence of collusion being presented and no Trump official being either indicted or cleared.

"There's a cloud hanging over Trump's administration and White House, unjustified," Buchanan said. "And I think he was telling, in effect, Comey, 'Look, get this done, get this over with. Exonerate me or indict somebody.' And I think Comey didn't do a thing and that's why he got rid of him."

Watch more from Buchanan in the clips above and below.

WATCH: CNN's Cooper Rolls Eyes at Conway During Interview on Comey

Russian Media Invited Into Trump's Closed-Door Meeting With Kremlin Officials

Students Stage Walkout After MN City Council Votes to Disband Local Police

Mainstream Media Accuses Trump of Abuse of Power, Fascism for Comey Firing