Independent Vermont Senator and top-tier 2020 Democratic primary leader Bernie Sanders said that like Donald Trump, he too would use tariffs as one of many negotiating tactics against China. However, he also said he thinks Trump’s behavior during trade negotations has been “irrational” and is damaging the economies at home and abroad.

Sanders appeared on CNN’s “State of the Union” this week to give an interview and make his case for why he should be in charge of negotiating with China as the President of the United States. He said tariffs are just one of many tools the president can wield and that “of course” he would use them.

“If it is used in a rational way within the context of a broad, sensible trade policy, it is one tool that’s available,” Sanders said before adding that he “helped lead the effort against permanent normal trade relations with China and NAFTA.

“We need a rational trade policy today, not what Trump is doing by tweet.”

Sanders, known as “Crazy Bernie” among Trump and his fans, called the president’s actions “totally irrational” and said they are “destabilizing the entire world economy.”

“You do not make trade policy by announcing today that you’re going to raise tariffs by X-percent, and the next day by Y-percent, by attacking the person you appointed as head of the Federal Reserve as an enemy of the American people, by denouncing the president of China, who last year you really loved as a great leader,” Sanders said.

“This kind of instability and irrationality on the part of the president is causing very serious harm to the entire world economy. Yes, we need a new trade policy.”

The Trump administration has said at nearly every turn that the president’s tariffs aren’t hurting U.S. consumers and only hurting China. However, Trump delayed the latest round of announced tariffs on a number of consumer goods popular at Christmas time until Dec. 15, and told reporters in France on Sunday that he had “second thoughts” about wielding the tariffs the way he has.

White House officials later backtracked on that statement and said Trump heard the question wrong in regards to his “second thoughts,” but delaying the tariffs on gifts popular at Christmas shows the administration is concerned it would hurt consumer spending and, in turn, the economy.