Sen. Bernie Sanders, I-Vt., says his presidential campaign is about much more than beating President Trump.

"That is not enough," Sanders said Sunday on NBC's "Meet the Press" when asked about Democratic rival Joe Biden's approach to global warming.

In a speech in Philadelphia the day before, Biden said: "If you want to know what the first and most important plank in my climate proposal is: Beat Trump."

Sanders argued that defeating Trump is only the first step.

"It goes without saying that we've got to defeat Donald Trump, who in my view is the most dangerous president in the modern history of this country. He's a pathological liar. He's a sexist and a racist, et cetera, et cetera," he said.

He continued: "But if we're talking, for example, about climate change, what the scientists tell us is we have 12 years before irreparable damage is done to this planet. Beating Trump is not good enough. You've got to beat the fossil fuel industry. You have to talk on all of those forces of the status quo who do not want to move this country to energy efficiency and sustainable energy."

"There is no 'middle ground' when it comes to climate policy," Sanders wrote on Twitter without directly naming Biden.

"I've never been middle of the road on the environment," Biden later contended, saying he has been talking about climate change since 1987. "Nobody has been more consistent about taking on the environment and a green revolution than I have."