Washington CNN  — 

Alan Dershowitz, a recent addition to President Donald Trump’s legal team, said Sunday that he plans to revive an 1868 argument used during former President Andrew Johnson’s impeachment trial when he is arguing on behalf of Trump on the Senate floor.

House Speaker Nancy Pelosi delivered the two articles of impeachment against Trump to the Senate last week, charging the President with abuse of power and obstruction of Congress. The Senate trial is slated to begin on Tuesday, where Republicans and Democrats are expected to battle over a resolution setting the rules for the trial and shortly after start opening arguments.

Dershowitz said on CNN’s “State of the Union” that he would be paraphrasing former Supreme Court Justice Benjamin Curtis, who served as the chief counsel during Johnson’s impeachment, in saying the framers of the Constitution intended for impeachable conduct to mean “criminal-like conduct.”

Dershowitz said he will argue that because the House charges do not include criminal conduct, there is no need for witnesses. If this reasoning prevails, he said, there would not be any reason for any further witnesses or arguments.

“(Curtis) argued successfully to the Senate that criminal-like conduct is required. That argument prevailed. I will be making that argument as a lawyer on behalf of the President’s defense team against impeachment. That’s my role. It’s very clear. I have done it before,” Dershowitz, a constitutional law professor at Harvard Law School, said.

Dershowitz’s argument hinges on the consideration by the Senate that neither of those charges qualify as “criminal-like conduct.”

Dershowitz also argued on ABC’s “This Week” that both obstruction of Congress and abuse of power are not within the constitutional criteria for impeachment as set forth by the founders. The Constitution says presidents can be impeached for “Treason, Bribery, or other high Crimes and Misdemeanors,” but it does not define “high crimes and misdemeanors.”

In his testimony to Congress in December, Harvard Law School constitutional law professor Noah Feldman said the phrase means “abuse of the office of the presidency for personal advantage or to corrupt the electoral process or to subvert the national security of the United States.” Under this opposing definition, the President’s conduct does not have to be criminal to be impeachable.

Dershowitz on Sunday made it clear that he would not be involved in the day-to-day with the legal team – noting that he will just be there to argue the specific issue of constitutional criteria for impeachment, making “what could be the most important argument on the floor.”

The President was especially fixated on having controversial defense attorney Dershowitz on the legal team. But Dershowitz has been telling his own associates he didn’t want to participate in the President’s trial, a source who is familiar with these conversations told CNN. White House officials have applied a lot of pressure over the last several weeks to convince Dershowitz to join the team, sources familiar with the attorney’s appointment said.

On Sunday, Dershowitz told CNN’s Brianna Keilar that he didn’t think his past clients – notable names like Jeffrey Epstein, former President Bill Clinton or O.J. Simpson – would affect his ability to make a persuasive argument to the Senate.

“I have defended some of the most controversial people in American history … I am very proud of my role as a defense lawyer. I did nothing wrong in any of those cases,” Dershowitz said.

CNN’s Kristen Holmes, Jim Acosta and Pamela Brown contributed to this report.