There was a particular focus on the environment during Sunday night’s Democratic debate in Flint, Michigan, and for good reason: Flint’s water crisis has been one of this year’s biggest environmental news stories.

For Hillary Clinton, the setting was an opportunity to try to separate her policy agenda from Bernie Sanders’ on the environment, an issue where she’s long been playing catch-up. Unfortunately, she failed spectacularly.

Take her long response to the short question “Do you support fracking?” for example:

“I don’t support it when any locality or any state is against it, number one. I don’t support it when the release of methane or contamination of water is present. I don’t support it, number three, unless we can require that anybody who fracks has to tell us exactly what chemicals they are using,” Clinton offered. “By the time we get through all of my conditions, I do not think there will be many places in America where fracking will continue to take place.”

Immediately, Bernie Sanders replied with a zinger: “My answer is a lot shorter. No. I do not support fracking.”

As Grist’s Rebecca Leber explains, that answer from Clinton is a significant shift from even her recent views on the topic—a sign she’s continuing to move further in Sanders’ direction on the environment. Such an equivocal answer from Clinton hides an important part of her environmental legacy: As President Obama’s secretary of state, she often served as fracking’s personal ambassador to the world. “Under her leadership, the State Department worked closely with energy companies to spread fracking around the globe,” wrote Mariah Blake in a 2014 feature for Mother Jones. Blake continues:

During a 2010 gathering of foreign ministers in Washington, DC, she spoke about America’s plans to help spread fracking abroad. “I know that in some places [it] is controversial,” she said, “but natural gas is the cleanest fossil fuel available for power generation today.” She later traveled to Poland for a series of meetings with officials, after which she announced that the country had joined the Global Shale Gas Initiative.

Fracking is the No. 1 reason why American oil and gas production has skyrocketed during Obama’s presidency. Methane leaks associated with fracking, meanwhile, are quickening climate change, and it’s profoundly changed the local landscape in countless locations across the world. The impact of fracking in North Dakota can be seen from space—even at night.

But the issue is nuanced. Environmental activists have long contended that the process of fracking—or, hydraulic fracturing, where water is injected into wells at high pressure to form tiny cracks in rocks and extract oil and gas—leads to widespread contamination of local water supplies. Last year, a comprehensive report published by the Environmental Protection Agency said that while that does happen in the United States, it’s not a widespread problem. That’s probably what Clinton was trying to get at in her long-winded answer. She probably could have done so without hiding from her own past as a fracking superfan.

Read more Slate coverage of the Democratic primary.