First Alan Dershowitz said you can be impeached without committing a crime. Now he says you can't be.

In August 1998, during the summer leading up to then-President Bill Cinton's impeachment, Dershowitz argued that a president does not have to commit a "technical crime" in order for it to constitute impeachable conduct.

"It certainly doesn't have to be a crime if you have somebody who completely corrupts the office of president and who abuses trust and who poses great danger to our liberty, you don't need a technical crime," Dershowitz told "Larry King Live."

He added: "We look at their acts of state. We look at how they conduct the foreign policy. We look at whether they try to subvert the Constitution."

But on Sunday he told CNN's Brianna Keilar on "State of the Union" that in his defense of Trump he would cite former Supreme Court Justice Benjamin Curtis in saying the framers of the Constitution intended for impeachable conduct to mean "criminal-like conduct."

Curtis served as the chief counsel during Andrew Johnson's impeachment.

Trump faces two articles of impeachment: abuse of power and obstruction of Congress. The Senate trial begins on Tuesday.

Dershowitz also asserted on ABC's "This Week" that both obstruction of Congress and abuse of power do not meet the constitutional criteria for impeachment.

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." Dershowitz's argument hinges on the Senate agreeing that neither of those charges qualify as "criminal-like conduct."

But Dershowitz has previously argued that a President's conduct does not have to be criminal to be impeachable. They simply had to "corrupt the office of president" or abuse trust.

On Monday, Dershowitz repeatedly denied that his position has changed since the Clinton impeachment days. He said he still believes Congress doesn't need a "technical crime" to impeach, but that they do need "criminal-type behavior" related to "treason and bribery" to meet the threshold for impeachment.

"It's the same argument," he said on MSNBC. "You need criminal-type behavior akin to treason and bribery. It doesn't have to be a technical crime because at the time that the framers wrote the constitution there was no criminal code."