In a move that is sure to draw the ire of Republicans, California officials are asking the Obama administration this week to approve a plan that would allow undocumented immigrants to buy health insurance on the state’s public exchange.

Officials say that up to 30 percent of the state’s two million undocumented adults could be eligible for the program, and that roughly 17,000 people are expected to participate in the first year, if the plan is approved. But the proposal faces serious hurdles in Washington, where it must be approved by both the Treasury and the Health and Human Services Departments.

During debates over health care in his first term, and again when Congress considered an immigration overhaul in 2013, President Obama made it clear that health insurance subsidies under the Affordable Care Act would not go to immigrants who are living in the United States illegally. And two provisions of the health care law limit coverage to residents who are here legally. But advocates of California’s initiative argue that the plan should be approved under what is known as an “innovation waiver,” which allows states to have provisions of the federal law modified, because no federal dollars will be used to fund the program.