President Trump will replace the nation's top anti-drug official Sunday, when Chuck Rosenberg steps down after more than two years leading the Drug Enforcement Administration, and marijuana partisans are anxiously awaiting his pick.

It's unclear who Trump will make acting administrator, or if that person will be a placeholder or a long-serving acting administrator like Rosenberg and his predecessor Michele Leonhart, who went three years without Senate confirmation.

What is clear: The appointee will lead a nearly 11,000-person agency at a pivotal moment, with anti-marijuana Attorney General Jeff Sessions reviewing the Obama administration's 2013 Cole Memo that allowed states to regulate recreational pot in violation of federal law.

Trump said during the 2016 campaign that he supports legal access to medical marijuana and state autonomy for recreational pot, despite his doubts about legalization. But as president, Trump has been silent amid repeated denunciations from Sessions.

"If the Justice Department is considering a new enforcement posture, the head of the DEA is likely going to have a strong voice in how that is designed," said Lewis Koski, a former director of Colorado's Marijuana Enforcement Division.

Koski, a cannabis regulation consultant, believes any crackdown would be a political minefield, and that while "marijuana is certainly going to be an issue they are addressing" the new leader's focus may be dominated by rising deaths from opioid abuse.

Cannabis researcher Dr. Sue Sisley shares that hope, but her optimism is tempered by years struggling with federal rules as part of a study on pot as treatment for post-traumatic stress disorder.

"This guy sets the tone for how the entire administration deals with cannabis," Sisley said of the DEA position.

"We hope that he will be removed, but if Sessions is allowed to persist in that role, we will need to have a DEA administrator who has a backbone to challenge Sessions on his antiquated thinking," she said.

From the other side, the stakes don't appear so high.

Kevin Sabet, an anti-marijuana-legalization organizer and former presidential drug policy adviser, said he believes the DEA appointee is unlikely to make major policy decisions.

"They are taking their orders directly from the attorney general, who is taking his orders directly from the White House," Sabet said. "If the president and Jeff Sessions together decide to shut down the marijuana industry, certainly there will be a role for the DEA but I'm not sure the administrator will make that call."

Sabet, leader of the national anti-legalization advocacy group Smart Approaches to Marijuana, added: "Too often folks want a boogeyman or boogeywoman in the drug war, and it's easy to point at the DEA for that, but in reality their ability to change policy is quite limited."

The DEA's roles include guiding where drugs belong in restricted schedules according to their danger and medical utility. Marijuana currently is in the most restricted category, Schedule I, making it difficult to research.

The agency also establishes quotas for production of illegal drugs for research and approves licenses for producers and researchers to handle drugs.

Among the candidates reportedly being considered to lead the DEA is New Jersey State Police Superintendent Rick Fuentes, but other people are said to be in the running. What Fuentes' long career in law enforcement would portend for cannabis policy is a matter of debate.

Despite some unease among reformers about what's next, Rosenberg was no liberal on drug policy, and small steps on medical research came amid controversial remarks, such as Rosenberg saying "I'm not an expert" about whether heroin was more dangerous than pot and saying that smoking marijuana as medicine was "a joke."

Although it allowed recreational sales pursuant to the 2013 Cole Memo and complied with a 2014 congressional spending measure protecting state medical pot programs, the DEA was by no means permissive under former President Barack Obama.

In 2012, DEA agents raided a family of medical marijuana growers in Washington state, busting them for slightly exceeding the state's cap on collective gardens. The family patriarch died of cancer, while three family members and a friend received federal prison terms. DEA agents in 2015 destroyed a Wisconsin American Indian tribe's field of what it said was industrial hemp, following a dubious field test.

But under Rosenberg, the DEA also took some small steps toward liberalization, easing resupply rules for researchers of cannabidiol (CBD), an anticonvulsant cannabis compound used by epileptics. The agency said last year it would end the single-farm monopoly on marijuana that's grown for research — although no new licenses have yet been issued.

Mason Tvert, a co-director of Colorado's legalization campaign and former spokesman for the Marijuana Policy Project, said he's hopeful that the next DEA leader will be more, rather than less, supportive of reform.

"The country's drug enforcement priorities should reflect the country's evolving relationships with drugs," he said. "Our nation cannot afford another DEA administrator who refuses to differentiate between marijuana and heroin."