The man likely to be the primary author of legislation repealing Obamacare refused on Sunday to promise that his “replacement” for the health care law would guarantee full coverage of birth control.

Appearing on CNN’s “State of the Nation,” House Speaker Paul Ryan (R-Wis.) faced pointed questions from host Jake Tapper about the new health care system Republicans have promised to create once they’ve taken the Affordable Care Act off the books.

In particular, Tapper wanted to know, would the new system require all insurance plans to cover FDA-approved forms of birth control, without any co-payments or other forms of out-of-pocket spending?

Such a requirement exists today because the health care law mandates that insurance plans fully cover “preventive services.” When the Obama administration wrote the regulations to fulfill that requirement, it put contraception on the list, on the theory that birth control was a routine form of health care ― women use it not just to prevent pregnancy but also, in many cases, to help with other medical conditions.

Ryan wouldn’t say yes or no to Tapper’s question, arguing that he couldn’t make promises about legislation that didn’t exist.

Here’s how the exchange went:

TAPPER: Obamacare also provides birth control to women at no cost. Is that going to end or will that remain? RYAN: Look, I’m not going to get into all the nitty-gritty details of these things. TAPPER: With all do respect, I don’t know that the average woman of child-bearing years out there who relies upon contraception provided by health insurance mandated by the Affordable Care Act, I don’t know that she would think that that’s just a nitty-gritty detail. That’s... RYAN: You’re asking me detail...

Tapper kept at it, asking Ryan whether he thought the benefit itself was something important. Again, Ryan wouldn’t answer:

TAPPER: Well, what do you think? Is it important to you? RYAN: Jake, you’re asking me details about legislation ― you’re asking me details about legislation that hasn’t been written yet. TAPPER: Right. But is it important to you? Would that be a principle? Would that be a principle of whatever replaces it, because... RYAN: I’m not going to get into ― I’m not going to get into hypotheticals about legislation that hasn’t even been drafted yet.

Studies have shown that the requirement, in place since 2013, has succeeded in reducing what people pay for contraception ― most likely increasing usage, particularly when it comes to the long-acting forms, such as intrauterine devices, that physicians consider most effective.

Polls suggest that the mandate, like most of the law’s consumer protections, is popular.

But like so many other provisions of Obamacare, it has also generated intense criticism from conservatives.

Some objected on grounds of religious freedom, arguing that employers who provide coverage to employees might object to paying for contraception because it violates the dictates of their faith.

The Obama administration addressed these by offering workarounds, so that certain religious employers could essentially opt out of paying for the requirement, but those employers have objected that even filing the necessary paperwork would violate their religious freedom.

Other conservatives object that the contraception requirement makes insurance more expensive overall. But while that’s certainly true for other insurance mandates the law has imposed on coverage, it’s unclear whether it’s also true of the contraception mandate, since birth control is relatively cheap and the costs associated with pregnancy are not. At the very least, many experts think, covering birth control at no cost may lead to lower health care spending overall.

Lurking beneath all of this is a more fundamental philosophical question at the heart of the health care debate ― to what extent should health care expenses be distributed broadly, and to what extent should they fall on the individuals who use them.

In 2009, during the legislative debate over the Affordable Care Act, some critics of the emerging legislation suggested it was wrong to make men pay for expenses like maternity care or contraception, since women are the ones who get pregnant.

The law’s promoters responded that men in fact have a direct stake in the well-being of women and children ― and that, given that human reproduction also requires the involvement of men, perhaps birth control should be partly their responsibility, too.

As it happens, the birth control mandate is one part of Obamacare that doesn’t require legislation to repeal. As Sarah Kliff of Vox noted recently, Trump could simply reverse the Obama administration’s regulation declaring that contraception belongs on the list of preventive services. It’s unclear whether Trump finds the contraception provision objectionable.