Immigrants should not be denied U.S. citizenship due to working in legal marijuana industries, a group of 10 senators told the Trump administration Tuesday.

“We write to oppose the United States Citizenship and Immigration Services (USCIS) guidance which ignores the will of Americans across the country by considering cannabis-related activities as a factor for the ‘good moral character’ standard required by immigrants seeking to naturalize, particularly in cases where there is no violation of state law,” they said in a letter sent to the heads of the Departments of Justice and Homeland Security.

“The federal government has long accommodated the different views Americans have across the country and have accordingly deferred to states to define laws and policies which best reflect their communities. To that end, we ask the Department of Justice and the Department of Homeland Security to prevent implementation of this USCIS guidance and to exclude cannabis-related activities as a factor in determining ‘good moral character’ for naturalization purposes,” they wrote.

Led by Sen. Ron Wyden of Oregon, the letter was signed by nine fellow Democrats: Sens. Elizabeth Warren of Massachusetts, Kirsten Gillibrand of New York, Patty Murray of Washington, Jacky Rosen and Catherine Cortez Masto of Nevada, Jeff Merkley of Oregon, Amy Klobuchar of Minnesota, Kamala D. Harris of California and Cory A. Booker of New Jersey.

Ms. Warren, Ms. Gillibrand, Ms. Klobuchar, Ms. Harris and Mr. Booker are running in the 2020 presidential election.

Representatives for the Justice Department and DHS did not immediately return messages requesting comment.

Thirty-three states have legalized the medicinal use of marijuana to varying degrees, including 10 where adults can legally use the plant for recreational purposes.

Marijuana is prohibited under federal law, however, complicating matters for stakeholders in state-legal medicinal and recreational industries across the country.

Listed under the U.S. Controlled Substances Act as a Schedule 1 drug, marijuana is classified alongside heroin and accordingly subjected to strict federal regulations in restrictions despite being legalized for medicinal or recreational purposes in most of the country.

Immigration officials issued policy guidance in April clarifying that a “violation of federal controlled substance law, including for marijuana, established by a conviction or admission, is generally a bar to establishing [good moral character] for naturalization even where the conduct would not be a violation of state law.”

An applicant “who is involved in certain marijuana related activities may lack [good moral character] if found to have violated federal law, even if such activity is not unlawful under applicable state or foreign laws,” USCIS said in a memo.

A bipartisan group of more than 40 members of the U.S. House of Representatives subsequently sent a similar letter last month to the heads of the Justice Department and DHS complaining about the policy guidance and calling it “fatally flawed.”

“We remain deeply concerned that the enforcement of the USCIS guidance during immigration proceedings will not accurately reflect the values of standards of the applicant’s community, especially if the applicant residents in a state or territory where cannabis is legal and where federal cannabis laws remain unenforced,” the senators echoed this week.