WASHINGTON, Jan 21 (Reuters) - Democrats who will argue the case to remove President Donald Trump from office demanded on Tuesday that Trump's personal lawyer Pat Cipollone disclose any first-hand knowledge he has of evidence he will present in the Senate's impeachment trial, calling him a material witness.

“You must disclose all facts and information as to which you have first-hand knowledge that will be at issue in connection with evidence you present or arguments you make in your role as the President’s legal advocate so that the Senate and Chief Justice can be apprised of any potential ethical issues, conflicts, or biases," the House of Representatives managers wrote in a letter to Cipollone. (Reporting by Lisa Lambert)