AUGUSTA — U.S. Rep. Chellie Pingree is asking the federal Health and Human Services secretary to block major cuts to Maine’s Medicaid program that Republican lawmakers and Gov. Paul LePage’s administration have been counting on to balance the state budget.

Pingree, a Democrat who represents Maine’s First Congressional District, wrote this week in a letter to Health and Human Services Secretary Kathleen Sebelius that the Affordable Care Act, the Obama administration’s signature health care reform law that was mostly upheld by the Supreme Court last month, prohibits states from scaling back existing Medicaid services.

Maine legislators this spring passed a supplemental budget bill that tightens eligibility requirements for MaineCare, the state’s Medicaid program. The cuts affect elderly and disabled people who receive assistance so they can afford prescription drugs and some low-income parents, and eliminate MaineCare coverage for 19- and 20-year-olds.

The move, which was estimated to save the state $20 million, would affect health insurance coverage for about 27,000 people. The cuts were among the measures used by lawmakers to plug an $83 million budget gap at the state Department of Health and Human Services.

“It is clear to me that the governor’s proposed elimination of Medicaid coverage would not only adversely affect the health and well-being of Maine residents and upset Maine’s local economies,” Pingree wrote in her letter to Sebelius, “it would also be in direct violation of the [maintenance of effort] requirement, even in the wake of the Supreme Court’s ruling.”

The maintenance of effort requirement is the provision in the federal health care law that requires that states maintain their current Medicaid coverage levels until 2014, when an expansion of the federal Medicaid program is slated to take effect under the health care law.

When LePage signed the budget bill, it was unclear whether Maine would be allowed to move ahead with the cuts under federal law. The administration had planned to seek a federal waiver that would allow the state to make the Medicaid cuts.

Now, however, the administration plans to move forward with the Medicaid cuts without a waiver, said LePage spokeswoman Adrienne Bennett.

While the U.S. Supreme Court last month upheld most provisions of the health care law as constitutional, the court ruled it was unconstitutional for the federal government to penalize states for not expanding Medicaid programs. The LePage administration is reading that part of the ruling as a sign it doesn’t need federal permission to make Medicaid cuts.

“The administration believes that we can do so, and there was clear indication from the ruling that outlines that,” Bennett said. “We will be moving forward with what has been approved by the Legislature.”

But Democrats disagree that the court ruling invalidates the prohibition on cuts to existing Medicaid services.

“It is important to note the [maintenance of effort] requirement is not discussed anywhere throughout the Court’s decision,” Pingree wrote to Sebelius. “What may be required of states through 2014 — including [maintenance of effort] requirements — remains untouched by this decision.”

Pingree urged Sebelius to develop guidance for states on implementing the Affordable Care Act.

“I strongly hope that you will reaffirm your commitment to the [maintenance of effort] requirement,” she wrote.