Harvard constitutional law professor Laurence Tribe on Wednesday took apart a key Republican argument against the impeachment of President Donald Trump over the Ukraine scandal .

Tribe, appearing on MSNBC s All In with Chris Hayes said some Republicans were missing the point by claiming abuse of power (one of two articles of impeachment that House Democrats have released against Trump, the other being obstruction of Congress) is not a crime.

It is the highest crime against the Constitution, said Tribe. And in this case the impeachment articles are carefully written to show the aggregating circumstances.

This isnt just using the presidents power to benefit himself, Tribe added. But its doing that in a way that endangers our national security and that corrupts the electoral process by inviting foreign involvement.

Tribe, who advised the House Judiciary Committee on how to draft the articles of impeachment, earlier explained why the articles were the classic high crimes and misdemeanors.

He said:

Abuse of power is what the impeachment clause was all about. The idea of using the power of the presidency not to protect the nation but to benefit ones self and especially ones reelection. In fact, in the debates around the framing of the Constitution, the big question about the impeachment power was do we really need it, or is it enough, because the president will have to stand for reelection if its going to be ahead of him? The answer to that was what if he corrupts the election process? What if he uses his power to reframe the election so that he rigs the system? We cant afford to wait. That was the whole reason not to wait for the quadrennial election to take place.

Tribe concluded by claiming that as a historic matter, this is the clearest case weve ever seen in the use of the impeachment power.

Especially when you add the second article, which basically says that if the president will not in any way cooperate with the process then we really do have a president who is a dictator and if this isnt impeachable, as many have said, then nothing is. Thats the theory of this case.

Check out the segment above.