According to their sources, the White House is prepping a proposal that would make it more difficult for immigrants to become citizens or receive a green card if they, or anyone in their household, has ever used social welfare services like plans provided by the Affordable Care Act, children’s health insurance, or food stamps.

The potential changes, credited to White House senior adviser Stephen Miller, would not need Congressional approval, NBC states. More than 20 million legal immigrants could be affected, particularly those with low incomes.

Data from the Department of Homeland Security’s Office of Immigration Statistics states that roughly 264,000 immigrants obtained lawful permanent resident status in the first quarter of fiscal year 2018, a 9% decrease from this period last year. Meanwhile, naturalizations in the first quarter numbered 163,000, a 55% increase from the same period last year.

According to CNN, Miller is behind a number of Trump’s most controversial moves, including the travel ban affecting a number of Muslim countries, the firing of former FBI director James Comey, and separating families at the border.

This latest move would appease to anti-immigration dogma that criticizes those who come to the U.S. and utilize the public welfare services to care for their families. This stigma has survived despite the fact that millions of immigrants, including those who are undocumented, pay taxes into the system that supports these programs.