SAN FRANCISCO – In a swift response to White House plans to give greater weight to an immigrant’s use of public assistance when deciding whether to approve green card applications, two Bay Area counties called the so-called “public charge rule” unconstitutional in a lawsuit filed Tuesday.

“The Trump administration’s new rule is an unlawful, foolish attack on immigrant communities,” Santa Clara County Counsel James Williams said in a statement. “It will hurt all members of our communities by reducing access to critical health and safety-net services that create healthier communities for all of our residents.”

Santa Clara joins San Francisco in a federal challenge to the U.S. Department of Homeland Security’s rule on “Inadmissibility on Public Charge Grounds,” set to apply to green card and visa applicants beginning Oct. 15.

The counties claim the rule redefines the longstanding meaning of a “public charge” – someone who relies on government assistance – to include reliance on food stamps, Medicaid and a list of other public benefits.

It also expands the factors considered in visa and green card applications to include family size, credit score, and even the application for welfare or food stamps.

“This abrupt shift in policy undermines the counties’ critical public health and safety-net systems, is arbitrary and capricious, flouts federal law, and seeks to usurp Congress’ authority by administratively repealing its longstanding family-based immigration system,” the counties say in their lawsuit.

The counties say the rule will coerce thousands of immigrants and their families to forgo or withdraw from county-administered welfare programs, as it sets the bar for benefits use “unreasonably low at 12 months of use within a 36-month period.”

Immigrant families will likely delay care for serious medical conditions, further straining the counties’ already overburdened emergency rooms, the counties claim.

The rule does carve out some circumstances in which the receipt of public assistance will not weigh against an immigrant’s application. These include people in the military and their families, people who receive Medicare Part D low-income subsidies, and pregnant women and people under 21 enrolled in Medicaid.

It also will not apply to refugees, those granted asylum, domestic violence and certain trafficking victims, and special immigrant juveniles.

“For over a century, the public charge ground of inadmissibility has been part of our nation’s immigration laws. President Trump has delivered on his promise to the American people to enforce long-standing immigration law by defining the public charge inadmissibility ground that has been on the books for years,” U.S. Citizenship and Immigration Services Acting Director Ken Cuccinelli said in a statement announcing the rule Monday. He added that the final rule will promote “self-reliance, industriousness and perseverance.”

San Francisco City Attorney Dennis Herrera condemned the rule on Tuesday, calling it “rubbish.”

“This rule forces people to make an impossible choice: their health or a better future for their family,” Herrera said. “We will all bear the cost of this misguided policy, which will shift millions of dollars in health care costs onto the taxpayers of San Francisco and Santa Clara counties. At the same time, it will siphon millions from our local economies and drive more people toward homelessness. This rule is rubbish.”

The counties want a federal judge to declare the rule unlawful and to permanently block its enforcement.