(CNN) Sen. Richard Blumenthal, a Connecticut Democrat who serves on the Senate Judiciary and Armed Services committees, said Tuesday that the country is in a "Watergate moment" and "we need bipartisanship now more than ever to protect the special counsel."

Michael Cohen, Trump's former personal attorney and fixer, pleaded guilty in federal court Tuesday to eight criminal counts of campaign finance violations, tax fraud and bank fraud and admitted he had acted to keep information that would have been harmful to Trump's campaign from becoming public during the 2016 presidential election.

"They could not accept Michael Cohen's plea agreement unless they believe Michael Cohen," Blumenthal told CNN's Wolf Blitzer on "The Situation Room," "which means they have evidence to corroborate it."

Blumenthal said the Senate Judiciary Committee needs to conduct its own investigation.

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