After Bernie Sanders’ defeat in the Pennsylvania primary this week, his campaign to win the Democratic nomination officially entered extreme ‘long shot’ territory. But even though his campaign will likely end without the nomination, it has succeeded in highlighting some of Sanders’ key issues, like income inequality and student debt.

Another issue Sanders has been hitting hard is fracking. “If we are going to preserve clean drinking water in this country, we have got to end fracking,” he told supporters at a campaign rally in Pittsburgh.

And Sanders isn’t the only Democratic politician to take a hard line on fracking in the state’s primary. U.S. Senate candidates John Fetterman and Joe Sestak both support a moratorium on fracking for environmental reasons.

But these three candidates also have another thing in common—they all lost their Pennsylvania primaries.

Sanders fell to Hillary Clinton, who, as Secretary of State, pushed the merits of fracking to U.S. allies; Fetterman and Sestak to Katie McGinty, the former head of the Pennsylvania Department of Environmental Protection, who is against a ban on fracking.

LISTEN: “Why Fracking Is—and Isn’t—a Winning Issue in the 2016 Election”

But increasingly, the public is turning against the oil and gas industry on the issue. A recent Gallup poll found that 51 percent of respondents were opposed to frackingup from 40 percent a year ago.

“You’re seeing more and more candidates step out on the issue because it’s more in step with what the public is thinking,” says Doug Shields, a former Pittsburgh city council president who authored the city’s 2010 fracking ban. When a politician garnering the kind of media attention Sanders has speaks out on fracking, Shields says it elevates the issue. “People start to pause and think about what exactly is going on.”

The oil and gas industry has dismissed the emergence of anti-fracking politics in the current primary election. The American Petroleum Institute’s Louis Finkel called the ‘ban fracking’ rhetoric “a political stunt by those who are spouting populist rhetoric for political points.”

So does this kind of campaign rhetoric impact actual regulation of fracking?

Experts say many of the laws that could be used to further regulate frackinglike the Safe Drinking Water Actwould have to be changed by Congress. But they also say states have a key role to play.

“Most of the action is at the state level,” says Jay Apt, a professor of engineering and public policy at Carnegie Mellon University.

In Pennsylvania, Gov. Tom Wolf is moving closer to signing tighter regulations on drilling, despite opposition from the state legislature. The state is also stepping up monitoring of air quality around oil and gas operations.

A recent Gallup poll found that 51 percent of respondents were opposed to frackingup from 40 percent a year ago.

Calls by politicians to ban fracking make some energy policy experts uneasy. Paulina Jaramillo, an assistant professor of engineering and public policy at Carnegie Mellon University, says she isn’t a fan of Sanders’ plan for fracking. That’s because natural gas, which produces fewer carbon dioxide emissions than coal, is key for the success of the Clean Power Plan—President Obama’s signature climate change initiative. Under that plan, natural gas use would go up, while coal use would go down.

“The Clean Power Plan relies on the availability of natural gas. So to just stay there’s a blanket moratorium on fracking—it’s just concerning,” Jaramillo says.

Jaramillo says there are real environmental concerns with natural gas developmentlike disposal of fracking wastewater. But blanket policies like a total ban on fracking are “ill-informed.”

“There’s risk in every energy resource,” she says. “With energy, we have to be very careful about absolutes. We have to be careful about any politics making claims that are not really based on the best science available.”