The Justice Department engaged in a “politically motivated and retaliatory demotion in January 2018 and public firing in March 2018,” Mr. McCabe said in his lawsuit.

He added that President Trump “purposefully and intentionally” pushed the Justice Department to demote and terminate him as part of an “unconstitutional plan” to discredit and remove Justice Department and F.B.I. employees who were “deemed to be his partisan opponents.”…

Earlier this week, Peter Strzok, the F.B.I. senior counterintelligence agent in the Russia investigations, also sued the Justice Department and the F.B.I. He said in his lawsuit that he had been terminated because of political pressure from the president, who was enraged by text messages that showed he had been a harsh critic of Mr. Trump.

“The F.B.I. fired Special Agent Strzok because of his protected political speech in violation of his rights under the First Amendment to the Constitution of the United States,” the lawsuit said. Mr. Strzok said his termination also violated his due process rights.