Even House Speaker John Boehner (R-Ohio) has acknowledged that the Affordable Care Act is the "law of the land," now that it has survived a Supreme Court challenge and a presidential election.
Ryan has also been selective in his willingness to use current law. His budget assumes that recent tax increases will remain in place, despite GOP opposition to passing them, but does not make the same assumption for the healthcare law, which is also the law of the land despite Republican opposition.
Ryan says the budget is a display of priorities, and that repealing the ACA and fundamentally overhauling Medicaid should remain top goals for the GOP.
Those cuts, if they took effect, would save the federal government roughly $2.5 trillion over the next decade.
According to estimates the Congressional Budget Office prepared last month, the Medicaid expansion under the ACA is set to cover 12 million new people by 2023.
"The health-care law would exacerbate the already crippling one-size-fits-all enrollment mandates that have resulted in below-market reimbursements, poor health-care outcomes, and restrictive services," Ryan's budget states.
Another 25 million people will gain access to private health insurance through newly formed exchanges, usually with help from a federal subsidy.
Ryan's budget proposal would repeal both the Medicaid expansion and the exchanges, as well as policies like the individual insurance mandate that offset the costs of those programs.
Repealing Obama's coverage expansion would save about $1.8 trillion, according to Ryan, while revoking healthcare coverage from 37 million people.
On top of repealing the ACA, Ryan would convert Medicaid into a block-grant program for the states. His budget compares the change to welfare reform, and it's a major cut — the federal government would save $756 billion over 10 years, according to Ryan's math.
The savings would come from a program that remains cheaper than private insurance, but that program's costs are expected to rise steadily over the next several years — especially as more people enter the system through the healthcare law's expansion.
An Urban Institute analysis of Ryan's previous budget proposals estimated that 14 million to 27 million people would lose their Medicaid eligibility under a block-grant proposal, bringing the total number to somewhere between 51 million and 64 million people.
The loss of coverage would fall primarily to low-income taxpayers, who are the primary recipients of Medicare as well as the healthcare law's subsidies.
Ryan's budget outline compares the Medicaid block grant to welfare reform in the 1990s.
"This budget applies the lessons of welfare reform to federal-aid programs," Ryan's proposal states. "It gives states more flexibility to tailor programs to their people’s needs. It gives those closest to the people better tools so they can root out waste, fraud, and abuse. Finally, it empowers recipients to get off the aid rolls and back on the payroll."