(CNN) House Judiciary Chairman Jerry Nadler said Monday that President Donald Trump has attacked the "core functions" of American democracy and that congressional Democrats will hold him and his administration accountable with a sweeping investigation.

"For two years the Trump administration has been attacking the core functions ... of our democracy, and the Congress has refused to do any oversight," the New York Democrat told CNN's Erin Burnett on "Erin Burnett OutFront."

The chairman announced on Monday a broad probe into the President's campaign, businesses, transition and administration. The sweeping investigation would lay the groundwork for the newly empowered Democrats if they chose to pursue impeachment proceedings against Trump.

Nadler said that Republicans -- who controlled both chambers of Congress until January, when Democrats took the majority in the House following their wins in November's midterm elections -- have "shielded" the President.

He said "our goal is to hold the administration accountable for the obstruction of justice," and "the abuse of power and the corruption."

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