Former Vice President Joe Biden struggled to explain his plan to persuade China to lower its carbon footprint on Wednesday.

Biden, who has fluctuated between downplaying China as an economic threat to warning they may soon outpace the U.S. in energy and infrastructure, was asked during CNN’s climate change town hall how he would pressure the communist power to address its carbon output—which is currently the largest in the world.

“I would make it real clear, that’s why we have to bring around the rest of the world, we have to reconfigure what’s going on,” Biden said, proceeding to argue international treaties like the Paris Climate Accord were a step in the right direction. “We have to up the ante of what’s going on.”

The former vice president added that China, like any other nation, that is unwilling to abide by global climate change standards would have to pay a “price.”

“I would talk about dealing with how the deal with them in terms of tariffs relating to their products that are being sold if in fact they are involved in continuing to export—export—this climate change,” Biden said, “But got to get the rest of the world in on the deal.”

Before the U.S. could hope to exert such pressure, Biden said, it would need to first meet those standards itself.

“You can’t very well preach to the choir if in fact you can’t sing,” the former vice president said. “We have to be able to demonstrate what we are prepared to do…and call the rest of the world to account.”

How does Biden have any solutions for China now when they walked all over the United States when he was in Congress I'm voting #Trump2020 #ClimateTownHall pic.twitter.com/CzB2s5nhBB — America's Voice News (@AVoiceNews) September 5, 2019

Biden’s argument in favor of increasing tariffs is surprising, especially since he’s criticized President Donald Trump in recent months for relying on the same strategy to curb China’s unfair trade practices.

“The president has done nothing but increase the tariffs, the debt, and the trade deficit,” Biden said during a campaign swing through New Hampshire in May.