Hillary Clinton is talking a big game about eliminating fracking, but energy experts aren’t buying her big promises to cut out the environmentally-questionable mining method, and say her actions don’t match her words.

Fracking was the centerpiece of this week’s debate in Flint, Michigan, where both Bernie Sanders and Hillary Clinton came out strongly against fracking.

Sanders was straightforward, saying he was strongly against it, but as Mother Jones noted, Hillary Clinton’s answer was more circuitous.

“Hillary Clinton, though, needed more time to outline three conditions in a more nuanced answer on fracking. She’s against it ‘when any locality or any state is against it,’ ‘when the release of methane or contamination of water is present,’ and ‘unless we can require that anybody who fracks has to tell us exactly what chemicals they are using.’ “Until those conditions are met, ‘we’ve got to regulate everything that is currently underway, and we have to have a system in place that prevents further fracking.'”

Clinton said that when all the conditions were in place, there were not many locations where fracking could work.

But energy experts don’t think Clinton’s words match her actions. In the past she has been more direct in her support of fracking, and many believe her speaking out against it now is simply a ploy to win over voters.

“Secretary Clinton’s answer is essentially campaign hyperbole, and meant to appease her environmental constituency,” Bruce Bullock, director of the Maguire Energy Institute at Southern Methodist University, told the Dallas Morning News, via Fortune. “In reality, it has little substance to it.”

Yong Jung Cho, the campaign coordinator of the grassroots group 350 Action, doesn’t think Clinton will convince many people that she has suddenly flip-flopped on fracking.

“Clinton will continue to struggle to convince climate advocates that she is serious about addressing the crisis until she comes out for a full ban on fracking,” said Cho.

It may be even harder for Clinton to make the case this week. Just days after Clinton publicly decried fracking, she attended a $575-a-plate fundraising lunch from an investment firm that invests heavily in fracking.

Clinton headlined the luncheon, held at a Ritz-Carlton Hotel and hosted by Alisa Wood, a partner at the international private equity firm Kohlberg Kravis Roberts & Co. (KKR). As The Intercept noted, KKR has been a heavy investor in fracking, selling shares of three North American oil and gas companies for billions in profits.

Hillary says she'd regulate fracking. Today a firm investing in fracking is hosting a fundraiser for her. https://t.co/0wVoJBKEpd — Zaid Jilani (@ZaidJilani) March 9, 2016

The flap over fracking could have played a major part in Hillary Clinton’s massive upset loss in Michigan, where she once led by a 20-plus point margin but ended up with a narrow loss to Bernie Sanders. As CNN noted, voters said trustworthiness was a major factor, and gave Clinton terrible marks on that front.

“In another troubling sign for the Clinton campaign, among voters who said their most important priority in a presidential candidate is that they are honest and trustworthy, Sanders overwhelmingly outperformed Clinton, 80% to 19%.”

The surprise win in Michigan may have done something else for Bernie Sanders. With the win, he has not bought time to continue attacking Hillary Clinton on her trustworthiness, and the events of this week showed that fracking may be a major point of attack.

[Picture by Alex Wong/Getty Images]