The Justice Department warned states they could lose billions of dollars in welfare funding if they do not report known illegal migrants to the federal government, according to a legal opinion released Wednesday.

The DOJ’s Office of Legal Counsel said tates participating in two key welfare programs must require all state agencies to report individuals known to be unlawfully present to the Department of Homeland Security, a significant shift that the administration says will help enforce President Donald Trump’s crackdown on illegal immigration. The opinion reverses a 1998 Office of Legal Counsel interpretation that limited the reporting requirement to agencies administering the programs.

Previously, only the state agencies that administered the funding for the welfare programs were required to report illegal migrants, while other state agencies that might be aware of these individuals, including colleges and departments of motor vehicles, were not subject to this mandate.

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“Failure to comply may lead to serious consequences, including loss of program funding,” Deputy Assistant Attorney General Joshua Craddock said in a statement.

Since returning to the White House, Trump has taken an aggressive approach targeting both illegal and legal immigration.

The president’s crackdown on illegal immigration has included deploying federal agents into cities across the country to conduct raids on migrant communities and increasingly partnering with state and local law enforcement and outside companies to locate suspected illegal migrants.

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The DOJ’s Office of Legal Counsel said all states that receive funding for two key welfare programs must report illegal migrants to the Department of Homeland Security. (John Moore/Getty Images)

The administration has repeatedly attempted to pressure Democrat-led states that have refused cooperation with federal immigration enforcement, including by threatening federal funding.

The shift could face legal challenges. Democrat-led states have already sued to block DHS from collecting personal details of people receiving funds under one of the programs, Temporary Assistance for Needy Families.

Courts have also limited some administration efforts to require the sharing of information on migrants with DHS. But in some cases, judges allowed federal immigration authorities to collect certain information, including Medicaid data.

Since returning to the White House, President Donald Trump has taken an aggressive approach targeting both illegal and legal immigration. (Photo by Jim WATSON / AFP via Getty Images)

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All 50 states and Washington, D.C., participate in the reporting requirements tied to the two programs: Temporary Assistance for Needy Families and Supplemental Security Income.

Federal Temporary Assistance for Needy Families grants exceed $16.5 billion annually, and Supplemental Security Income federal benefits exceed $60 billion annually.

Illegal migrants are not eligible for either program.

Reuters contributed to this report.