"He's turning his back on $4 billion" a year in federal health care money, said House Minority Leader Frank Dermody, D-Allegheny, adding that Corbett's fears of a growing state share are "overstated."
Corbett, a Republican who will run for re-election next year, faces a potential primary challenger from the right and heavy pressure from conservatives to resist elements of "Obamacare."
As attorney general in 2010, Corbett joined an ultimately unsuccessful multi-state lawsuit to try to throw out President Barack Obama's sweeping health care law. The U.S. Supreme Court upheld the heart of the law last year, but allowed states to decide whether to expand Medicaid.
The administration says the cost to Pennsylvania would be $4.1 billion over eight years, while Democratic lawmakers say the state treasury would see a net benefit of $670 million a year in higher tax revenues from the economic boost to the health care sector and lower state costs to cover people who are uninsured.
The expansion would allow Pennsylvanians earning up to 133 percent of the federal poverty level, or about $30,000 for a family of four, to be eligible for Medicaid coverage.