Story highlights Former FBI Director James Comey will testify on the Hill on Thursday

Other officials, including Sen. John McCain, have made similar Watergate comparisons

(CNN) Sen. Ron Wyden, a Democrat on the Intelligence Committee, said President Donald Trump's alleged attempt to interfere in ousted FBI Director James Comey's Russia investigation is almost "Watergate-level."

Comey on Wednesday released an opening statement ahead of his appearance before the Senate intelligence committee. In it, the former FBI official, who was leading the investigation into Russia's meddling into the 2016 election, wrote that Trump asked him to pledge his loyalty. Comey also said the President asked him to stop investigating ex-national security adviser Michael Flynn, and to publicly declare that Trump was not under investigation.

"It is a remarkable statement," Wyden, an Oregon Democrat, told CNN's Jake Tapper on "The Lead" on Wednesday. "It reads more like a Tom Clancy novel than your usual garden-variety congressional testimony. For example, Comey confirms that Trump asked him to end that investigation into Flynn. That by itself is almost a Watergate-level effort to interfere with an ongoing investigation."

When asked if he thought Trump potentially obstructed justice, Wyden said, "I'll tell you, if it looks like a duck, and it quacks like a duck, it just might be a duck."

He went on to criticize Trump's interactions with Comey.

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