"The health reform law will reduce the number of uninsured people by an estimated 32.9 million, leaving 27.1 million people uninsured," the report said. By contrast, "Nationally, Romney's proposals are estimated to increase the number of uninsured people by 12 million compared with the baseline (no Affordable Care Act), leaving 72 million people uninsured in 2022."
The Commonwealth Fund study concluded that repealing the Affordable Care Act -- which would unwind the subsidies and market reforms to expand coverage and roll back the law's expansion of Medicaid -- would swell the ranks of the uninsured. Taken together, Romney's other proposals to convert Medicaid into a block grant and equalize the tax treatment of employer-provided and individually-purchased insurance would add to that.
The report also assumes that all states will ultimately accept matching funds to expand their Medicaid programs as the ACA calls for -- despite the fact that June's Supreme Court ruling effectively made the expansion optional.
The comparison is based on methods crafted by Jonathan Gruber, a leading health economist at the Massachusetts Institute of Technology who advised policymakers who designed the Affordable Care Act, and has since criticized Romney's turn against a national version of the blueprint he enacted as governor of Massachusetts.
The Commonwealth study sought to fill in the blanks of Romney's proposals where they were vague, such as the rate of growth in the Medicaid block grant and how much states will need to cut. The Romney campaign disputed its assumptions.
"The Commonwealth study sadly contributes little to the health reform conversation that this country deserves," Romney spokeswoman Andrea Saul told TPM. "It badly mistakes Governor Romney's proposals. Worse, it assumes a fantasy world where Obamacare has been a success. Instead, Americans have seen their insurance premiums increase, small businesses are facing massive tax increases, and seniors will have reduced access to Medicare services. The simple truth is this: The American people do not want this law, we cannot afford this law, and when Mitt Romney is President he will repeal it and replace it with common-sense, patient-centered reforms that strengthen our health care system."