Naomi Klein, the Canadian social justice activist and best-selling author, declared in a new interview that, when it comes to climate, she does not trust Hillary Clinton.

In an interview preview aired Tuesday, Klein argues that Clinton’s corporate ties make her a “vulnerable” candidate for the presidency and that Democratic rival Bernie Sanders is a “significantly better candidate.”

“I think that Bernie Sanders could win in a general election,” Klein told Mehdi Hasan, host of Al Jazeera‘s “UpFront.”

“The logic of her candidacy,” Klein said, “was because she had so much money. A lot of it was just, ‘she’s unbeatable—look how deep the pockets are.'”

“I don’t trust her because as secretary of state, when she had a huge megaphone to make this an issue, to show that she understands the connections between human security and climate, she didn’t use the megaphone.”

The “irony,” Klein explains, is the sources of that money and “the entanglement of the Clinton Foundation, with so many corporations and so many governments,” is precisely what makes her “vulnerable.”

“So, on the one hand, it’s what supposedly makes her inevitable. And on the other hand, it’s what I think makes her a very weak candidate and makes Bernie Sanders a much better candidate,” she said.