The Trump administration is working on a proposal that would make it harder for legal immigrants to obtain citizenship or acquire green cards if they’ve used public welfare programs, including Obamacare, according to a new report.

A draft of the plan described to NBC News shows the administration could prevent immigrants living legally in the U.S. who have used Obamacare, children’s health insurance and food stamps, among other benefits, from obtaining citizenship. Using Social Security Insurance already made it harder for immigrants to get legal status.

White House senior adviser Stephen Miller is spearheading the proposal, which NBC said would not need approval from Congress.

Immigration lawyers, advocates and public health researchers told NBC News the proposal could affect more than 20 million immigrants.

"The administration is committed to enforcing existing immigration law, which is clearly intended to protect the American taxpayer by ensuring that foreign nationals seeking to enter or remain in the U.S are self-sufficient. Any proposed changes would ensure that the government takes the responsibility of being good stewards of taxpayer funds seriously and adjudicates immigration benefit requests in accordance with the law,” a spokeswoman for the Department of Homeland Security told the news outlet.

The Trump administration is currently on track for a 20 percent decrease in immigrants who are granted green cards for fiscal year 2018 compared to the last full fiscal year under former President Barack Obama. Naturalized citizenship is expected to drop by 10 percent during the same time period.