An agreement between moderate Republicans and GOP leadership in the House to allow a vote on extending expiring Affordable Care Act (ACA) subsidies is on the rocks as the two sides squabble over the contents of the amendment.

Rep. Brian Fitzpatrick (R-Pa.) and other GOP centrists are planning to introduce an amendment in the House Rules Committee on Tuesday that pairs a two-year extension of the subsidies with eligibility reforms, according to a House GOP staffer who spoke on the condition of anonymity.

But GOP leadership insisted the extension needed to be offset with spending cuts — a demand the moderates balked at. Conservatives opposed to extending the subsidies have frequently cited the cost, which is estimated to be at least $35 billion per year.