(CNN) Congressional Democrats are ratcheting up their criticism of the classified GOP memo alleging the FBI abused its surveillance authority, ahead of President Donald Trump's looming deadline to decide whether to release the document to the public.

Sen. Ben Cardin, D-Maryland, said Republicans are trying to compromise the independence of the Justice Department with their push to release the memo, which was spearheaded by House Intelligence Chairman Devin Nunes.

Asked in an interview on CNN's "New Day" Wednesday if he was prepared for the memo to come out, Cardin said, "To me this is sad and dangerous."

"We're talking about defending the rule of law, defending the independence of the Department of Justice," said Cardin, the top Democrat on the Senate Foreign Relations Committee. "You would think Congress would stand up for the independence for the Department of Justice."

He added, "It looks like the Republicans are prepared to compromise our system in order to protect the President."

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