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CMS on Tuesday announced a new effort to clean up public health insurance programs, to sweep ineligible immigrants from Medicaid and the Children’s Health Insurance Program (CHIP). The aggressive new initiative, which was first previewed to reporters by CMS officials on Monday, is one of the Trump administration’s boldest efforts in his second term yet to restrict access to taxpayer-funded benefits to eligible U.S. citizens and lawfully present individuals.

The enrollment verification program will flag Medicaid and CHIP enrollees across the country whose immigration or citizenship status is undetermined by federal agencies. Going forward, CMS will issue enrollment reports to each state monthly, and the Social Security Administration and Department of Homeland Security’s Systematic Alien Verification for Entitlements (SAVE) will be among the sources used to confirm eligibility.

The first reports were issued on Tuesday, the agency said, with each state receiving a report monthly and then expected to conduct its own determinations to confirm eligibility of the enrollees in question. States must verify status with CMS, and the agency said that enrollees must “either be removed from the program or have their eligibility confirmed.”

“We are strengthening oversight of enrollment to protect taxpayer dollars and ensure these critical programs only serve individuals who are eligible by law,” HHS Secretary Robert F. Kennedy Jr. said in a statement.

CMS Administrator Dr. Mehmet Oz concurred. “Every dollar misspent is a dollar diverted from an eligible, vulnerable individual in need of Medicaid and CHIP,” he said. “This is our latest action to demonstrate an unyielding commitment to program integrity, protect taxpayer dollars, and ensure that taxpayer-funded benefits go to those who are eligible by law.”

The announcement comes as President Donald Trump’s second term has been marked by an aggressive series of executive actions and regulatory changes to rein in illegal immigrant access to federal benefits, one of the Republicans’ top immigration priorities in recent years. In February, Trump signed one of his first executive orders since the start of his second term, calling on all federal agencies to review public benefits programs to identify how they could better ensure non-citizens were not unlawfully receiving benefits, which would run afoul of the 1996 Personal Responsibility and Work Opportunity Reconciliation Act.

The Department of Health and Human Services soon expanded that definition in a rule change that month, identifying 44 programs that would count as public benefits to a previous list of 31. And now, Democrats are fighting back with lawsuits and other political maneuvers to protect access to those programs.

Last month, for example, a federal judge ordered the Department of Health and Human Services to cease sharing enrollee data with ICE and other immigration authorities. That information sharing began this year, with the Trump administration claiming the right to use Medicaid data to assist in deportation efforts. The federal judge, however, said the practice went beyond the agency’s remit.

States are also under new statutory obligations as a result of a big-ticket spending bill Republicans were able to pass last month over Democratic objections. That package required states to conduct eligibility determinations on Medicaid recipients at least twice per year, an increase from past benchmarks. While supporters of the move say it will help prevent fraud and abuse, opponents say it is nothing more than bureaucratic busywork that will hurt the most vulnerable patients and families.

In fact, more than 20 attorneys general in Democratic-led states have already filed suit against the administration over the new CMS rules, with New York Attorney General Letitia James leading the charge. James and her allies have called mandatory verification of immigration status for federally funded public programs a threat to access for millions of state residents.

“For decades, states like New York have built health, education, and family support systems that serve anyone in need,” she said in a statement in late March. “These programs work because they are open, accessible, and grounded in compassion. Now, the federal government is pulling that foundation out from under us overnight, jeopardizing cancer screenings, early childhood education, primary care, and so much more. This is a baseless attack on some of our country’s most effective and inclusive public programs, and we will not let it stand.”

CMS has thus far already sent out its first monthly enrollment reports as the legal fights and political standoffs continue in state capitols across the country. While some of the Democrats’ actions are likely to play out in court, Medicaid and CHIP are also likely to remain political flashpoints in the ongoing battle over illegal immigration in Congress and Washington.