Democratic presidential hopeful Bernie Sanders, who’s repeatedly accused Donald Trump of being a divisive “demagogue,” opened a new line of attack Monday night on the Republican front-runner: lampooning his views on climate change.

Appearing at a rally here, Sanders referenced a three-year-old statement from Trump in which the real-estate mogul asserted that “the concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive.”

“What an insight,” the Vermont senator told his audience in a sarcastic tone. “How brilliant can you be. The entire scientific community has concluded that climate change is real and causing major problems and Trump believes that it’s a hoax created by the Chinese. Surprised it wasn’t the Mexicans.”

Sanders, who is challenging Hillary Clinton for the Democratic nomination, has increasingly been using Trump as foil in campaign speeches. At the same time, Sanders is seeking to reach out to working-class Trump supporters, arguing he would better represent them on economic issues.

Trump has responded in kind, calling Sanders a “wacko” among other things.

Sanders’s latest jab at the billionaire came as he wrapped up a two-day swing through New Hampshire, the first primary state, where recent polls have showed Sanders with a modest lead over Clinton, the former secretary of state.

Sanders has also recently taken aim at Trump for his proposals to temporarily ban Muslims from coming into the country and to deport undocumented immigrants en masse.

“I say to Donald Trump, that ain’t what this country is about,” Sanders told his audience Monday night of more than 800 people at a community college.