Former FBI Director James Comey urged people to "use every breath we have" to make sure "the lies stop" and President Donald Trump is not reelected in 2020.

He also urged Democrats to choose a nominee that would beat Trump.

He said, however, that impeachment could leave some Americans feeling like there had been a "coup."

Comey, a vocal Trump critic, said the president was "certainly close" to being an unindicted co-conspirator in crimes identified in the Russia probe.

He also said he had become "numb" to Trump's criticisms of him.

Former FBI Director James Comey urged people to "use every breath we have" to prevent US President Donald Trump from being reelected in 2020.

Comey told MSNBC's Nicole Wallace on Sunday night, as cited by CNN: "All of us should use every breath we have to make sure the lies stop on January 20, 2021," referring to the next presidential inauguration day.

Comey, a former Republican and frequent Trump critic who now identifies as nonpartisan, urged Democrats to choose the candidate best suited to defeating Trump in the election.

"I understand the Democrats have important debates now over who their candidate should be," Comey told Wallace, "but they have to win. They have to win."

Trump in August. Win McNamee/Getty Images

He added that he was worried that a third-party candidate, like Michael Bloomberg, could take away enough votes from a Democrat to let Trump win, The Daily Beast reported. "That's Donald Trump's reelection strategy," he said.

Comey has been vocal on his feelings about the president's truthfulness and has previously said that Trump is known for "lying about all things" and compared the president to a "mob boss" that has a need for "complete control" — a comparison he repeated in Sunday's interview.

Read More: Comey says anyone who thinks the FBI favored Hillary Clinton in its emails investigation is 'smoking something' Comey said that he wanted Trump out of office, but not impeached. He said that removing Trump in a landslide vote would "rid ourselves of this attack on our values," but that removal by impeachment would "muddy that." Removing Trump by impeachment, he said, could leave many across the US with the feeling that their leader was removed in a "coup." But he also ruled out the possibility that he might run for election himself. "I'm never gonna run," he said. President Donald Trump and then-FBI Director James Comey , during an Inaugural Law Enforcement Officers and First Responders Reception in the White House in January 2017. Andrew Harrer-Pool/Getty Images

Russia probe

Comey, who Trump fired as FBI Director in 2017, also discussed recent key developments in the bureau's probe into the Trump presidential campaign's ties with Russia, such as the new sentencing memos for former Trump allies Michael Cohen and Paul Manafort.

Federal prosecutors on Friday recommended "substantial prison time" and a $100,000 fine for longtime Trump lawyer Michael Cohen, who pleaded guilty to financial crimes, campaign violations, and lying to Congress.

They also accused Manafort, the former chairman of Trump's presidential campaign, told prosecutors "discernible lies" about his contacts with the White House, breaching his cooperation agreement.

When asked if Trump could be an unindicted co-conspirator in some of the crimes described by Special Counsel Robert Mueller, Comey said he did not know, but said of Mueller: "If he's not there, he's certainly close."

Read More: Incoming top Democrats predict impeachment and jail time for Trump with increasing confidence

James Comey testifies in Washington DC in 2016. Win McNamee/Getty

Comey also responded to Trump lashing out at him on Twitter earlier on Sunday, in which he accused Comey of lying to Congress in testimony he delivered on Friday about his role in investigating Hillary Clinton's email server and the Trump campaign's potential ties to Russia.

Trump, who repeatedly referred to Comey as "Lyin' James Comey," said that key points of Comey's testimony were "all lies" and called him "Leakin' Comey."