Sen. Jeff Sessions (R-Ala.) has outlined his stance as a firm opponent of marijuana, but during his confirmation hearing Tuesday, he offered only vague answers about how he might approach the drug should he be confirmed as President-elect Donald Trump’s attorney general.

Although Sessions appeared to suggest there wouldn’t be radical changes in federal policy toward weed, he also left the door open for increased federal interference.

“I won’t commit to never enforcing federal law,” said Sessions, responding to a question about whether he’d use federal resources to prosecute people using marijuana in accordance with their state laws. “But absolutely it’s a problem of resources for the federal government.”

Sessions went on to say that federal guidelines on marijuana enforcement crafted under Attorneys General Eric Holder and Loretta Lynch had been “truly valuable” in determining how to navigate inconsistencies between federal law ― under which marijuana is illegal ― and state laws that have loosened restrictions on the plant. Sessions also noted that if Congress wanted to clear up this confusion, it could pass a law adjusting the legal status of marijuana. Until then, however, he vowed to do his job “in a just and fair way” while judging how to approach marijuana going forward.

“It is not so much the attorney general’s job to decide what laws to enforce,” Sessions said. “We should do our job and enforce laws effectively as we are able.”

Marijuana advocates met Sessions’ stance with guarded optimism, though they cautioned that he had not ruled out the possibility of more aggressive action against legal marijuana states and users.

“It’s a good sign that Sen. Sessions seemed open to keeping the Obama guidelines, if maybe with a little stricter enforcement of their restrictions,” said Tom Angell, chairman of Marijuana Majority, a drug policy reform group. “The truth is, his answer was skillfully evasive, and I hope other senators continue to press for more clarity on how he would approach the growing numbers of states enacting new marijuana laws.”

Bill Piper, senior director of national affairs for the Drug Policy Alliance, said Sessions was “wishy-washy at best.”

“It is clear that he was too afraid to say the Reefer Madness things he said just a year ago (that’s progress), but he left the door open to interfering in the states,” Piper said in an email. “I think he will follow Trump’s lead, whichever way that goes.”

Marijuana remains illegal under the federal Controlled Substances Act, despite statewide efforts to scale back on criminalizing the plant over the past few years. Legal recreational marijuana has been approved in eight states and Washington, D.C., which continues to ban sales, unlike the state programs. A total of 28 states have legalized marijuana for medical purposes. President Barack Obama’s Justice Department has allowed states to forge their own way on marijuana policy due to guidance urging federal prosecutors to refrain from targeting state-legal marijuana operations. But marijuana advocates are concerned that this guidance will be reversed when the Trump administration enters the White House and a new attorney general, presumably Sessions, takes control of the department.

His answer was skillfully evasive, and I hope other senators continue to press for more clarity. Tom Angell, chairman of Marijuana Majority

Sessions has long held retrograde views on marijuana and the war on drugs, and his nomination as attorney general had received near universal condemnation from advocates in favor of progressive drug policy.

“Jeff Sessions is a nightmare,” said Piper in a statement Monday. “He is a threat to progress, especially marijuana reform, sentencing reform, and asset forfeiture reform.” Piper urged the committee to reject Sessions’ nomination and was not swayed by the senator’s testimony on Tuesday.

During a Senate hearing last year, Sessions spoke out against weed and urged the federal government to send the message to the public that “good people don’t smoke marijuana.” He went on to criticize Obama for not speaking out more forcefully against the drug, saying that “we need grown-ups in Washington to say marijuana is not the kind of thing that ought to be legalized.” In separate comments last year, Sessions also called the legalization of marijuana “a mistake.”

Sessions told PBS’s “Frontline” in a 2015 interview that he believes the war on drugs was a success. But public support for the nation’s longstanding enforcement-first approach to drug use has waned in recent years. The four-decade boondoggle has cost the U.S. more than $1 trillion, cemented America’s position as the world’s leading jailer and ruined countless lives, while failing to drive down addiction rates or the price or purity of drugs.

If confirmed, Sessions would sit atop the Department of Justice, the federal agency that oversees federal prosecutors and enforces federal marijuana law. He would have great influence in determining whether to preserve or roll back recent changes to marijuana policy ― changes that reflect shifting public opinion in favor of more lenient weed laws.

Drug policy reformers have raised concerns that Sessions could use the FBI to crack down on marijuana operations nationwide, or direct the Drug Enforcement Administration to enforce federal prohibition outside of the jurisdiction of the U.S. Court of Appeals for the 9th Circuit. The court ruled in August that a federal rider blocks federal officials from prosecuting state-legal marijuana operators and patients. But that rider must be re-approved annually, and if it’s allowed to expire, Sessions could then order the DEA to enforce federal law nationally. He could also sue the various state governments that have set up regulatory schemes.

Sessions offered few details about his plans during his confirmation hearing on Tuesday, and some of his supporters have said it’s likely that he’ll take a hands-off approach toward marijuana. Rep. Dana Rohrabacher (R-Calif.), a vocal proponent for reforming marijuana laws, told The Huffington Post in November that Sessions would not interfere with states that have legalized marijuana, a position that he characterized as consistent with Trump’s.

“Jeff Sessions is a loyal man with integrity, he will do what his boss wants him to do,” Rohrabacher said.

During the presidential campaign last year, Trump said that he believes states should decide on marijuana legalization for themselves.

“In terms of marijuana and legalization, I think that should be a state issue, state by state,” Trump said.

Trump’s incoming press secretary, Sean Spicer, echoed similar sentiments on Tuesday during an interview on Fox News.

“When you come into a Trump administration, it’s the Trump agenda you are implementing, not your own, and I think Sen. Sessions is well aware of that,” he said.