The US government's institutions are "under assault" by President Donald Trump following his decision to fire FBI Director James Comey, former director of National Intelligence James Clapper said Sunday (14 May).

"I think, in many ways, our institutions are under assault, both externally — and that's the big news here, is the Russian interference in our election system. And I think as well our institutions are under assault internally," Clapper said.

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"Internally from the president?" Tapper asked.

"Exactly," Clapper responded. "I think the Founding Fathers, in their genius, created a system of three coequal branches of government and built-in system of checks and balances. And I feel as though it's under assault and eroding."

In a separate interview with ABC's This Week, Clapper said that Russia likely views Comey's firing as "another victory on the scoreboard for them" because "the lead of the investigation about potential collusion between Russia and the Trump campaign has been removed."

According to The New York Times, Clapper rejected Trump's repeated citing of his Senate testimony in dismissing the FBI investigation into potential connections between Russia and Trump's campaign. Clapper repeated that he did not know about the FBI's investigation until Comey revealed it publicly.

"The bottom line is, I don't know if there was collusion, and I don't know of any evidence to it," Clapper said. "I can't refute it, and I can't confirm it."

However, Trump took Clapper's testimony to mean something different. "When James Clapper himself, and virtually everyone else with knowledge of the witch hunt, says there is no collusion, when does it end?" the president tweeted on Friday (12 May).

Clapper insisted on ABC that the FBI would not have necessarily told him about their investigation. "I had no evidence available to me that there was collusion, but that's not necessarily exculpatory since I did not know the state of the investigation or the content—what had been turned up with it," he said.

Clapper also rebutted the White House's claim that Comey had lost the support of the FBI's rank and file. He said that Comey's sudden dismissal was "very disturbing" to bureau employees.

A new NBC News/Wall Street Journal poll released on Sunday reveals those outside of Washington also disapproved of the decision. The poll found that 38% of Americans disapproved of Trump's decision, while 29% approved.

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