The Biden administration has raised questions about Gov. Brian Kemp’s proposed changes to the Affordable Care Act marketplace in Georgia, including his plan to block Georgians’ access to the healthcare.gov shopping website.

More than 500,000 Georgians got their 2021 insurance on the marketplace, and most of them bought their plan on the federal website.

In a letter to Kemp Thursday, the U.S. Centers for Medicare and Medicaid Services cited changes in the landscape that have occurred since Kemp first filed the proposal: changes in Georgia’s insured population, in federal spending on marketing and outreach to promote enrollment, and in federal rules that relate to the ACA. CMS asked Georgia to re-evaluate some of its data and submit a new analysis by July 3.

That makes the second time one of Kemp’s two big health care “waiver” proposals that were approved by the Trump administration has run into trouble with the Biden administration. Both were controversial changes, and experts are not surprised.

In February the Biden administration put a pause on a Kemp-Trump waiver plan to change Medicaid in Georgia.

The proposals are called “waivers” because federal law allows the president to waive some parts of health care law to better serve an individual state’s citizens.

Kemp’s waiver proposals for the ACA insurance marketplace in Georgia were approved by the Trump administration in November and were set to go into effect over the next two years.

For the ACA marketplace, Kemp proposed that when Georgians try to shop for insurance plans on the ACA marketplace website healthcare.gov, they be blocked from shopping there. Instead, he proposed that the site direct shoppers to a list of private insurance agencies or companies where they could shop.

The waiver doesn’t create any new companies: Shoppers can already buy their ACA insurance directly from private agents. But the plan assumes that by canceling healthcare.gov shopping, the private companies that people shop with will improve their outreach and publicity.

The Biden administration took issue with that. “In its application, Georgia neither quantified the size of the expected investment by the private sector nor indicated any specific commitments by the private sector to engage in outreach and marketing,” the letter said.

ACA waivers by law must stay within certain “guardrails,” including that they won’t harm coverage and won’t increase the federal deficit. The data that the letter asked Georgia to provide could show whether the waiver would still meet those guardrails, given the recent changes.

That data includes information on the age, income and health insurance status of the relevant state population, along with an explanation of the key assumptions the state used to develop estimates of the effect of the Georgia access model.

The Georgia ACA waiver is already the subject of a federal lawsuit.

Kemp’s ACA waiver also has a less controversial provision called “reinsurance,” a state subsidy to insurance companies that could lower premium costs, especially for higher-income policyholders. The Biden administration left that provision alone. Policyholders are expected to see those lower prices in November 2022, as they begin shopping for 2023 plans.