Marijuana legalization backers fear the worst for their fast-growing industry as the U.S. Senate prepares to vote Wednesday to approve a longtime pot opponent, Alabama Republican Sen. Jeff Sessions, as the nation’s next attorney general.

All signs indicate that Sessions, who last year said that “good people don’t smoke marijuana,” has lined up the votes to get confirmed as the highest law enforcement officer in the land.

Sen. Jeff Sessions, R-AL, testified on Tuesday at a Senate Judiciary Committee hearing on his nomination for attorney general in the Donald Trump administration. “I can be trusted to do what I say I will do,” Sessions said. Protesters shouted him down twice during opening remarks.

No one’s sure exactly what that would mean for California, Washington and the six other states that have approved recreational marijuana, or the 28 states that allow the drug to be used as medicine.

And Sessions has done nothing to clear the uncertainty.

At his confirmation hearing in January, Sessions gave conflicting signals on whether he would follow the lead of President Barack Obama’s Justice Department in allowing states to tax and sell marijuana without federal interference, or whether he’d lead a new national crackdown by enforcing the federal law that bans all possession and sales of pot.

“There’s a lot of nervousness,” Adam Spiker, executive director of the Southern California Coalition, a marijuana trade association group based in Los Angeles, said Monday. “First and foremost, he’s made it real clear that he is not a fan of the product or the industry.”

He said the state of California, which approved medical marijuana in 1996 and recreational marijuana just last year, “has spoken very clearly” on the subject of legalization.

“Our group is comprised of hundreds and hundreds of businesses that want to stop looking over their shoulder,” Spiker said. “They want to be treated like any other business.”

Kevin Sabet, who heads the anti-legalization group Smart Approaches to Marijuana, is among the many who say it’s impossible to predict what Sessions might do.

“I think there will be changes, but no one can say how those changes will manifest themselves,” he said Monday.

In Washington state, where voters were the first to legalize recreational marijuana in 2012, along with Colorado, many politicians worry about a possible crackdown.

Both of the state’s Democratic senators, Maria Cantwell and Patty Murray, plan to vote against Sessions. Cantwell said Sessions’ testimony on legalizing and regulating marijuana before the Senate Judiciary Committee last month “left questions about the Trump administration’s approach to these issues.”

As a presidential candidate, Trump said that he would leave the question of legalization to individual states. But his choice of Sessions in November set off immediate panic among legalization backers.

When Sessions was asked at his confirmation hearing whether he would use federal resources to investigate and prosecute sick people who use medical marijuana, he replied: “I won’t commit to never enforcing federal law.”

But he also said that enforcing the law is “a problem of resources for the federal government.” And he said that Obama’s Justice Department had set out policies that are “truly valuable in evaluating cases.”

Sessions also said that Congress should set marijuana policy and the attorney general should enforce the law.

“I think one obvious concern is that the United States Congress has made the possession of marijuana in every state, and distribution of it, an illegal act. … We should do our job and enforce laws effectively as we’re able,” Sessions said.

In California, Spiker said that legalization supporters are banking on Trump’s view to prevail in his administration, regardless of what Sessions might want to do.

“The new president has made it real clear that he sees cannabis as a states’ rights issue,” Spiker said. “We’re hopeful that he’ll lead the charge.”

Other legalization backers hope that the sheer size of the industry – its market value is expected to approach nearly $22 billion by 2020 – will make it politically impossible to stop.

“The accepted logic in the marijuana industry is that the industry has grown too big to put the cat back in the bag,” Aaron Herzberg, partner and general counsel of Calcann Holdings, LLC, a California medical marijuana real estate company, said Monday.

But he added that it’s hardly a certainty and that growing public support for legalization provides no guarantee of what might happen, either.

“Those who have been in the industry for years have seen the federal government take aggressive positions on marijuana that are contrary to public opinion,” Herzberg said.