McCabe, 49, was expected to leave sometime early this year when he became fully eligible for a pension, after two decades in the bureau. Trump targeted McCabe with critical tweets after it emerged that his wife had received a campaign contribution for a race in Virginia in 2015 from an ally of Trump rival Hillary Clinton.
McCabe and fired FBI director James Comey had key roles in the FBI's probe of Clinton in the 2016 election, which ultimately cleared the Democrat of criminal wrongdoing in her misuse of a personal email server while she was secretary of state.