"They violated the free speech provision. They violated the impeachment criteria. They violated the bill of attainder. They violated due process, on and on and on." —Alan Dershowitz To Newsmax TV: House Violated Constitution
”14th Amendment, Section 3: No person shall be a Senator or Representative in Congress, or elector of President and Vice President, or hold any office, civil or military, under the United States, or under any State, who, having previously taken an oath, as a member of Congress, or as an officer of the United States, or as a member of any State legislature, or as an executive or judicial officer of any State, to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof. But Congress may by a vote of two-thirds of each House, remove such disability."
"rebellion: open resistance to an established government or ruler."
Or maybe they can just pass a Bill of Attainder that declares that Donald J. Trump may not hold any federal office during the remainder of his life.
Trump or his attorneys (if he can find any lawyers willing to take his case) could challenge a Bill of Attainder on the basis of Article I, Sec. 9 of the Constitution ("No Bill of Attainder or ex post facto law shall be passed.") But the enhanced 15-member Supreme Court (after Stacy Abrams, Sheila Jackson-Lee, Michelle Obama, Hillary Clinton, Elizabeth Warren and Adam Schiff have been added) will vote 10-5 against Trump.