Andrew Harrer/Bloomberg via Getty Images Homeland Security Secretary Kirstjen Nielsen has said the proposed rule change would “promote immigrant self-sufficiency and protect finite resources by ensuring that they are not likely to become burdens on American taxpayers.”

The Trump administration is following through on a long-rumored plan to make it harder for immigrants to get green cards if they’re poor or might become poor.

The proposal is a double whammy that could scare people away from safety net programs and keep immigrants out of the country ― with the added benefit of simultaneously demonizing both immigrants and welfare.

″It’s an opportunity to fuel the nativist fire and scapegoat immigrants as a drain on our economy,” said Wendy Cervantes, senior policy analyst for the Center for Law and Social Policy, a nonpartisan organization that works to improve the lives of low-income people.

The U.S. government has almost always had a rule against legal permanent resident status for anyone who might become a “public charge,” meaning someone who is likely to wind up on welfare. The proposed rule, which will not take effect for at least 60 days and is subject to change, would broaden the criteria the government can use to deny applicants.

The proposal will likely scare immigrants out of applying even for benefits that wouldn’t hurt their green card chances, Cervantes said, such as food stamps for their children. Already, officials in several states have reported sharp declines in child nutrition program enrollment that they attribute to earlier news reports about the possibility of a new “public charge” rule. (The final proposed rule considers only an individual’s use of public benefits, not any use by their dependents.)

Experts said it’s impossible to estimate how many people will be affected by the rule, but some said it could be in the millions ― some directly because they would be denied a green card, others indirectly because they declined to use a benefit out of fear or because a family member was kept away.

The Department of Homeland Security said in its proposal that it estimated more than 324,000 people would disenroll from safety net benefits “due to concern about the consequences to that person receiving public benefits and being found to be likely to become a public charge,” saving the federal government more than $2 billion annually. (That’s less than 1 percent of what the government spends on food and health benefits for the poor each year.) The proposed rule wouldn’t make those individuals ineligible for public benefits ― the administration is predicting it would cause people to not use help even if they were qualified for it.

Cervantes said the proposal as written would affect several million people if you count a program beneficiary’s family members. More than 40 percent of the nearly 40 million food stamp recipients in the U.S., for instance, are children whose parents receive the benefits on their behalf.

Immigrants could be fearful of enrolling their families in certain benefits even if they wouldn’t have an adverse effect on a future immigration decision, either because of confusion about what is included or fear that it could be expanded in the future, said Melissa Boteach, senior vice president at the left-leaning Center for American Progress, who works on poverty issues.

“People are confused, and the stakes are too high for them to make an educated guess,” Boteach said. “I think there’s a sense that even if you are technically exempt, who knows what they’ll do next?”

Undocumented immigrants and people on work visas are ineligible for most federal benefits in the first place, and green card holders are only eligible after five years. The proposal would not affect people applying to become U.S. citizens. It primarily targets people abroad hoping to be reunited with family members living in the U.S. and those already living here and seeking green cards.

In fiscal 2017, the State Department initially denied more than 280,000 immigrant visa applications. Of those, only 3,200 were refused on public charge grounds, according to the Congressional Research Service (most of those refusals were overcome on appeal). Cervantes said the number of public charge refusals would likely skyrocket under the new proposal.

The current public charge guidance considers a person’s age, education, assets and employment status, as well as his or her current enrollment in a small number of state and federal programs. Republicans have long complained that the biggest programs, such as food stamps and Medicaid, were excluded. The Trump administration’s rule would broaden the criteria to include most federal safety net benefits.

Department of Homeland Security Secretary Kirstjen Nielsen said in a statement announcing the proposal that it would “implement a law passed by Congress intended to promote immigrant self-sufficiency and protect finite resources by ensuring that they are not likely to become burdens on American taxpayers.”

The current guidance says an immigrant would only count as a public charge if he or she is likely to depend “primarily” on government assistance, meaning for more than 50 percent of his or her income. The new rule would lower the threshold to receipt of government benefits totaling 15 percent of the poverty line in a given year.

The meaning of “likely” is entirely up to immigration officials, said David Bier, an expert at the libertarian Cato Institute who wrote in an analysis of the proposal.

“They just are very vague about how this whole thing is going to go down,” Bier said in an interview. “So inevitably what we’re going to see when this rule is enforced is just wildly varying outcomes depending on who’s adjudicating applications.”

Roque Planas contributed reporting.