President Trump firing FBI Director James Comey is a scandal worse than Watergate, and represents an abuse of power, according to George W. Bush's chief ethics lawyer.

"Of course it's worse than Watergate," Richard Painter told CNBC. "[In] Watergate, we didn't have a foreign power, much less the Russians, conducting espionage inside the United States. That's what we had in 2016."

Painter said this controversy also has echoes of the Alger Hiss scandal, where a high-ranking State Department official was accused of being a communist spy. Though the scandal was discovered after the statute of limitations had expired, Hiss was convicted of perjury for lying about his actions.

"This is as if you took Watergate, rolled it into the Alger Hiss scandal and put it all in one," Painter said. "This is a very dangerous situation."

The ethics lawyer said it's clear that Russia has been attempting to "destabilize our democracy since the 1920's," and was only successful this time because they received help from people within the U.S. Whether those people are connected to Trump needs to be investigated, he said.

"The president cannot fire the FBI director while he's being investigated by the FBI director," he argued on "Power Lunch." "This is an abuse of power."

Painter said he also isn't buying the Trump administration's claim that one of the reasons Comey was terminated was his handling of the FBI investigation into Hillary Clinton's private email. The president, Painter said, would be "high-fiving" Comey if he thought the investigation did aid in his election.

The real reason, he said, is clear.

"It's about Russia, we know it's about Russia, and they're lying to us if they tell us anything different," Painter said.

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