ST. PAUL, Minn. — Minnesota Gov. Mark Dayton blasted federal health officials Wednesday for holding up approval of a program meant to lower health insurance costs and threatening millions of dollars in cuts to health care for the working poor.

State lawmakers tackled a precarious health insurance market on their own this year, creating a $542 million reinsurance pool to help lower costs for 2018 after years of inflating premiums for shoppers who buy coverage on their own. But Minnesota is one of just two states to also offer a so-called basic health program — covering low-income residents with the help of extra federal dollars — and it’s causing the state problems.

Despite assurances that final signoff would come by August, state officials are still awaiting formal approval as open enrollment fast approaches. And after working closely with the federal Department of Health and Human Services to ensure that the state’s other health programs wouldn’t be affected, Dayton’s administration revealed this week that President Donald Trump’s administration planned to cut almost $370 million from that low-income health coverage.

The Democratic governor called the situation a nightmare, saying the holdup in approval could cause premiums for 2018 to jump an estimated 20 percent. And he said the federal government has been little help in addressing his concerns.

“I can’t get the secretary of Health and Human Services on the telephone. I can’t even get a phone number to call him on,” Dayton said.

Minnesota’s issues are largely separate from the ongoing effort in Congress to repeal and replace President Barack Obama’s Affordable Care Act. But that makes them no less pressing.

Open enrollment begins Nov. 1, but MNsure — the state’s health insurance exchange — needs to start loading information for 2018’s health plans into its systems much sooner. Health insurance rates are set to be finalized Oct. 2.

Other officials are adding to the pressure on the nation’s top federal health agency. Democratic U.S. Sen. Amy Klobuchar said Tuesday she urged Health and Human Services Secretary Tom Price to approve the waiver immediately.

A spokeswoman for the federal agency did not immediately respond to a request for comment.

Dayton and others were clearly flummoxed by the Trump administration’s sudden move to cut a sizable chunk of federal funding for MinnesotaCare. State officials worked with the federal agency to write the reinsurance bill, saying they were repeatedly assured that it would not result in any cuts to federal funding.

But Dayton’s administration said that changed last week when they were informed — with little explanation — that the state would lose roughly $369 million in funding for the next two years. Dayton sent Price a letter Tuesday asking him to reconsider.

The governor wouldn’t answer whether he thought those cuts were politically motivated. Any changes to MinnesotaCare funding wouldn’t impact its roughly 100,000 low-income enrollees until at least 2019.