“Well, the first bill we’re going to be working on is our Obamacare legislation,” Ryan said in an interview on CBS’ 60 Minutes.

But what’s less clear is how Congress plans to actually make good on this vow. In the interview with CBS correspondent Scott Pelley, Ryan was light on specifics. Ryan said that it will be important to preserve a sufficient “transition period [from Obamacare] so that people can get better coverage at a better price,” but he didn’t specify how long that transition period would be. There have been reports that it could take as long as three years.

Nor did Ryan describe the GOP’s alternative to a health care plan—flaws notwithstanding—which has extended coverage to about 20 million Americans. Ryan insisted that Republicans will preserve some of Obamacare’s most popular and expensive provisions, such as allowing Americans to remain on their parents’ health plans until age 26 and barring insurers from refusing to cover people with pre-existing medical conditions, but that position—also held by President-elect Donald Trump—is confusing and perhaps unrealistic. If Congress gets rid of the mandate requiring Americans to be insured, insurance companies could find themselves with the financially untenable scenario in which people only buy insurance when they get sick.

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So how does a Republican-led Congress envision the next stage of U.S. healthcare reform? Ryan may be holding his cards close to the vest. But there are some clues, based on past proposals from Ryan and Trump’s pick to lead the Department of Health and Human Services (HHS), Georgia Congressman Tom Price. And even a unified GOP government may find them difficult to implement since a number of the proposals that would cut government-mandated benefits could run into serious opposition from powerful lobbying groups like seniors.

Medicare and Medicaid could be scaled back drastically. There’s been a lot of focus on Obamacare’s individual insurance marketplaces over the years. But the reality is that these markets are a tiny slice of both Obamacare itself and the overall U.S. insurance market since the vast majority of Americans are covered through their employers or public health programs like Medicare and Medicaid.

The latter program, a state-federal partnership established during President Lyndon Johnson’s presidency, will probably be scaled back significantly under a Trump presidency. Ryan has consistently advocated for, not just repealing Obamacare’s optional expansion of Medicaid, which has severely cut the uninsurance rate among the poorest working adults in the country, but turning the entire program into a “block grant.” That means that state governments will have far greater authority to slap restrictions on who can qualify for Medicaid (for instance, by cutting guaranteed health benefits and forcing beneficiaries to pay health premiums).

Obamacare’s individual marketplaces are likely doomed, too. Ryan’s proposed healthcare plans have involved vouchers or coupons to help people who don’t have employer or public coverage to buy insurance, and the expansion of Health Savings Accounts (HSAs) to cover out-of-pocket costs; he’s also advocated for allowing insurers to sell their plans across state lines, arguing this will foster competition and help bring down costs. There’s a bit of confusion about how government assistance will work for people buying individual plans—Ryan’s “Better Way” healthcare proposal pegs the level of assistance to age alone, and not income (Obamacare plans consider both). But Ryan seemed to suggest that income should be a consideration during his 60 Minutes interview.

Obamacare went through a roller coaster legislative process when it was first being crafted. It appears that a potential replacement—whenever it may be implemented—may face just as interesting of a path.