Washington CNN  — 

President Donald Trump’s attorney Alan Dershowitz on Tuesday shot back at Sen. Elizabeth Warren after the Massachusetts Democrat assailed his presentation in Trump’s Senate impeachment trial as hard to follow and tweeted that his argument is “contrary to both law & fact.”

“Warren doesn’t understand the law,” he tweeted Tuesday. “My former colleague, Senator Warren, claims she could not follow my carefully laid out presentation that everybody else seemed to understand. This says more about Warren than it does about me.”

Dershowitz alleged that Warren, his former colleague at Harvard Law School, “willfully mischaracterized what I said,” adding that “it’s the responsibility of presidential candidates to have a better understanding of the law.”

The pointed comments from Dershowitz come after Warren told reporters that his lengthy argument on the Senate floor Monday night was nonsensical. Dershowitz used his presentation to assert that even if Trump “were to demand a quid pro quo as a condition to sending aid to a foreign country, obviously a highly disputed matter in this case, that would not by itself constitute an abuse of power.”

He added: “Quid pro quo alone is not a basis for abuse of power, it’s part of the way foreign policy has been operated by presidents since the beginning of time.”

It’s unusual to hear an attorney on one of the legal teams in an impeachment trial directly criticize the senators who are acting as jurors, but Dershowitz’s comments only add to the partisan tensions that have plagued Trump’s trial.

Last week, Trump’s legal team slammed House Judiciary Chairman Jerry Nadler, a New York Democrat who is one of the House impeachment managers, for accusing Republican senators of being complicit in a cover-up of Trump’s behavior by voting against having witnesses. On Friday, GOP senators themselves reacted negatively to Rep. Adam Schiff, a California Democrat who’s the lead impeachment manager, quoting from a news report that stated a Trump adviser had told Republican senators they would face dire repercussions for crossing the President.

The presence of Dershowitz on Turmp’s legal team was a surprise announcement just before the impeachment trial began. Trump was especially fixated on having Dershowitz, a controversial defense attorney, on his legal team but Dershowitz had been telling his own associates he didn’t want to participate in the trial, a source who is familiar with these conversations told CNN.

White House officials had 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.

His short tenure defending Trump, however, has been largely defined by a series of contradictory statements from his past.

Earlier this month, he told CNN’s Anderson Cooper that he is “much more correct right now” in his current views on what qualifies a president for impeachment than in his nearly opposite views during the Bill Clinton impeachment.

“I didn’t do research back then, I relied on what professors said … because that issue was not presented in the Clinton impeachment,” Dershowitz said. “Everybody knew that he was charged with a crime, the issue is whether it was a hard crime. Now the issue is whether a crime or criminal-like behavior is required.”

He continued, “I’ve done the research now – I wasn’t wrong (at the time), I am just far more correct now than I was then. I said you didn’t need a technical crime back then. I still don’t think you need a technical crime.”

CNN’s Daniella Diaz, Caroline Kelly and Jamie Ehrlich contributed to this report.