WASHINGTON — Mark Kleiman, who served as Washington state’s top pot consultant after voters legalized the drug in 2012, says it would be easy for the next president to get rid of the nation’s marijuana shops.

“Look, a President Trump could shut down the legal cannabis industry everywhere in the country with the stroke of a pen,” said Kleiman, who’s now a professor of public policy at New York University’s Marron Institute of Urban Management. “All you have to do is take a list of the state-licensed cannabis growers and sellers into federal district court and say, ‘Your Honor, here are the people who have applied for and been given licenses to commit federal felonies.’ ”

Across the country, pot legalization advocates worry that a Donald Trump victory on Nov. 8 could mean trouble for legalized recreational pot in Washington state and Colorado, as well as other states such as California and Nevada that want to follow their lead.

If a new administration decides to enforce federal laws that ban the possession and sale of marijuana, pot backers say it could stall the national momentum for legalization and chase investors away from the nascent industry.

While Trump and his Democratic rival, former Secretary of State Hillary Clinton, both say they’d follow the lead of President Barack Obama in leaving legalization to states, many fear that the GOP presidential nominee could easily reverse course. They note Trump’s ties to two of the country’s most ardent opponents to legalization: New Jersey Republican Gov. Chris Christie and Sheldon Adelson, a multibillionaire casino magnate from Las Vegas.

Adelson caused a stir in December when he bought the Las Vegas Review-Journal, Nevada’s largest newspaper. Two weeks ago, the paper shocked marijuana backers by reversing its long history of support for legalization.

Kleiman said legalization backers in Washington state and elsewhere will have plenty of reason to worry if Trump wins and starts taking advice from Adelson on marijuana issues.

“I’m so old I can remember when billionaires were not a branch of government,” Kleiman said. “I mean, it is shocking that somebody can intervene in politics that way, but it’s true.”

Nevada is one of four states that will vote on the legalization of recreational marijuana this year, along with California, Arizona and Maine. It could be the biggest year yet on the marijuana front, with the number of states that allow fully legal pot possibly doubling.

Currently, Washington state, Colorado, Oregon, Alaska and the District of Columbia have legalized recreational marijuana. A majority of states now allow medical marijuana; Ohio became the 26th this month.

Kleiman said that while Clinton’s been cautious on marijuana issues, she’s given no indication that she would move to crack down on states that have legalized marijuana. And if the uncertainty surrounding Trump causes legalization backers to vote against him, Kleiman said: “I’m all for it.”