Under Trump's proclamation, immigrants would need to obtain private health coverage within 30 days of entering the United States or otherwise prove that they can cover their health care costs. The president also has insisted that the order be implemented even if courts find parts to be illegal.

"It is the policy of the United States to enforce this proclamation to the maximum extent possible to advance the interests of the United States," the president proclaimed on Oct. 4.

HHS did not respond to questions about whether staff had raised concerns about the new immigration requirements. “HHS will continue to work with the State Department to implement the president’s proclamation," a spokesperson said.

The White House and the State Department did not immediately respond to requests for comment.

More than two dozen health officials are wrestling with highly technical questions, like which health plans would comply with the new requirements and whether to adjust the enrollment period when immigrants can sign up three weeks before the policy is set to take effect.

Two individuals said the policy change has been championed by immigration hardliners inside the administration, led by White House senior adviser Stephen Miller, and not the health department's leaders. HHS Secretary Alex Azar and Centers for Medicare and Medicaid Services Administrator Seema Verma have previously raised internal concerns about the administration's immigration policies putting health care services at risk, a point that HHS disputed Friday.

"Politico’s reporting about Secretary Azar’s position and the assertion that he ‘raised internal concerns’ on this topic is blatantly false," said HHS spokesperson Caitlin Oakley. "It's not part of the health care agenda. It's clearly part of the immigration agenda."

Trump's proclamation also would bar immigrants from using Obamacare subsidies to purchase health plans and instead steer them toward alternatives touted by the Trump administration, like skimpier short-term plans. Health officials say that presents new technical hurdles, given that HealthCare.gov — the federal website created to shop for individual coverage — can't accommodate Obamacare alternatives. "We can't link directly to those plans," said an official, speaking on condition of anonymity.

Health officials have weighed directing immigrants to seek out guidance from consulates, given the many uncertainties. But it's not clear that the State Department even has the authority to carry out the order, said two individuals with knowledge of the discussions, since it would require steering immigrants toward health plans, tracking their use of coverage and other regulatory responsibilities traditionally driven by HHS.

The health insurance test could significantly limit legal immigration, if it takes effect, since many current visa-seekers lack the means to also pay for health coverage. "This new policy has the potential to block fully two-thirds of those who apply for legal permanent residence from abroad," the Migration Policy Institute concluded in an analysis this week.

Health department officials already are grappling with Trump's separate "public charge" order, which would deny green cards to legal immigrants who have received public benefits like Medicaid or who are deemed likely to do so in the future. The rule was scheduled to take effect on Oct. 15 but was stayed nationwide on Friday — buying time for officials to figure out how to meet that rule's complexities.

"One issue we have with public charge is how do you let people know that by signing up, they may be at risk for being penalized," said an official, who spoke on condition of anonymity. "We're struggling with how to get that done."

The administration's sweeping immigration agenda has repeatedly created problems for the health department; last year's order for border officials to separate migrant families and place the children in HHS custody sparked lawsuits and multiple congressional investigations that are still ongoing. The policy also traumatized separated children and led to other health care harms, the department's inspector general has found.

Senior Trump appointees this week publicly moved to distance the president's health insurance mandate from HHS.

"It's not part of the health care agenda. It's clearly part of the immigration agenda," Joe Grogan, director of the Domestic Policy Council, said at a press briefing this week. Verma — whose agency oversees health insurance markets — declined to answer whether her agency had analyzed the effects on insurance enrollment and said she'd defer to the State Department.