House Republicans have unveiled the cost-saving centerpiece of Trump’s “big, beautiful bill,” at least $880 billion in cuts largely to Medicaid to help cover the cost of $4.5 trillion in tax breaks.

Tallying hundreds of pages, the legislation revealed late Sunday is touching off the biggest political fight over health care since Republicans tried but failed to repeal and replace the Affordable Care Act, or Obamacare, during Trump’s first term in 2017.

While Republicans insist they are simply rooting out “waste, fraud and abuse” to generate savings with new work and eligibility requirements, Democrats warn that millions of Americans will lose coverage. A preliminary estimate from the nonpartisan Congressional Budget Office said the proposals would reduce the number of people with health care by 8.6 million over the decade.