When Dr. Cecilia Norris, a primary care physician in Iowa City, Iowa, sees a patient who wants an intrauterine device or a contraceptive implant, she takes out a pad and writes down the phone number for Planned Parenthood. Because of limited staff and resources, Norris can’t offer these forms of contraception at the free clinic where she works as the medical director, and most of her patients don’t have the money to get them anywhere else. “If you’re uninsured, like many of my patients, Planned Parenthood is the only remotely affordable option in town,” Norris said.

This could change if GOP lawmakers make good on a ubiquitous campaign promise: defunding Planned Parenthood. The House Republicans’ plan to replace the Affordable Care Act, announced Monday, would bar reproductive health care providers who offer abortion from receiving federal Medicaid reimbursements for one year. Although no federal money is spent on abortions except in cases of rape, incest or where the mother’s life is at risk, about 40 percent of Planned Parenthood’s revenue for other services — including contraception, sexually transmitted infection testing and cancer screenings — comes from the government, mostly through Medicaid. Because Medicaid is jointly financed by the states and the federal government, Congress’s action wouldn’t cut off all public funds to Planned Parenthood — states could even make up the difference if they wished. But some states have already made an effort to stop funding Planned Parenthood, and more are poised to follow suit: A bill pending in Iowa’s House of Representatives would cut off state Medicaid funding for abortion providers, a move clearly targeting the state’s 12 Planned Parenthood clinics.

The proposed cuts would affect large numbers of Planned Parenthood patients, many of whom are low-income. According to 2014 data from Planned Parenthood, three-quarters of the organization’s patients had incomes at or below 150 percent of the federal poverty level, and about 60 percent access its services for free or at a low cost through Medicaid or Title X, a federal family planning program that accounts for a smaller proportion of Planned Parenthood’s funding. Losing some or all of these patients would be a huge blow to the organization, which would likely have to close clinics or scale back services — affecting all of its patients, regardless of income.

When responding to critics who say that low-income women won’t be able to get care without Planned Parenthood, Republican leaders such as House Speaker Paul Ryan have pointed to a simple solution: federally qualified health centers, which receive government funding and provide care to patients regardless of their ability to pay. At a CNN town hall in January, Ryan said that shifting funding to these health centers, which offer family planning in addition to broader primary care services, would give women more options, because there are far more community health centers than Planned Parenthoods nationwide. In Iowa, state Sen. Amy Sinclair made a similar argument, saying that other health care sites that don’t provide abortion would be able to pick up the slack.

Federal community health centers are “vastly bigger in network, there are so many more of them, and they provide these kinds of services without all of the controversy surrounding this [abortion] issue,” Ryan said in January.

Reproductive health care experts, though, say it’s a mistake to view Planned Parenthood and community health centers as interchangeable simply because they both offer government-subsidized contraception. Instead, they say, it’s more accurate to consider Planned Parenthood part of a vast health care ecosystem, where it has made itself indispensable by providing one thing — reproductive health care — well.

“Community health centers, unlike Planned Parenthood, have an obligation to see everyone in their communities for everything,” said Sara Rosenbaum, a professor of health policy at George Washington University. “Ideally you want community health centers working hand in glove with organizations like Planned Parenthood, not replacing them.” Removing Planned Parenthood from the fabric of the health care system wouldn’t just mean that community health centers would have to scale up their family planning departments; they’d have to be prepared to offer a full range of services. This could be an ambitious and expensive goal.

The question of whether community health centers would be able to provide reproductive health care in lieu of Planned Parenthood isn’t entirely hypothetical. Texas provided a dry run, of sorts, when it embarked on a series of efforts to divert funding away from Planned Parenthood in 2011. First, the legislature instituted broad cuts to family planning services, spurring the closure of 82 clinics, one-third of which were affiliated with Planned Parenthood. Then, after an attempt to steer funds away from Planned Parenthood in the state’s federally funded Medicaid program was stymied by the federal government, Texas decided to forgo federal Medicaid dollars for family planning and set up a state-funded Medicaid lookalike called the Texas Women’s Health Program, which could legally exclude any clinic affiliated with an abortion provider. Iowa is considering a similar move: It would also create a women’s health network with no federal Medicaid support and no participation by abortion providers.

Texas’s example foreshadows what could happen if the Republicans’ defunding proposal goes through and states and localities don’t step in to fill the gap. It’s hard to know exactly how many low-income women rely on Planned Parenthood; in Iowa, Planned Parenthood served 62 percent of women who received publicly funded contraception from a safety-net center in 2010, according to an analysis by the Guttmacher Institute, a research organization that supports abortion rights. Since then, some Iowa Planned Parenthood facilities have closed, and more women may have gained insurance under the Affordable Care Act, so the numbers aren’t up to date. Supporters of the Iowa bill say 221 existing health care sites are eligible to offer family planning care under their plan. But even if the same amount of money is being spent on family planning, some women, when faced with a loss of coverage at Planned Parenthood, may not continue receiving services at other local clinics — either because of a lack of capacity or a lack of knowledge about where to go.

“When the funding cuts went into place [in 2013], my clinic was already maxed out — we weren’t accepting new patients,” said Regina Rogoff, CEO of Austin People’s Community Clinic in Texas. This is not atypical: A recent study of appointment availability for new patients at primary care practices showed that about 60 percent of practices surveyed in Texas were able to accommodate new Medicaid patients. Rogoff added that it’s expensive and time-consuming to expand facilities and add staff. “It’s definitely not something you can do overnight. You’re talking six to nine months just to find more clinicians.”

Then there’s the fact that even if they are accepting new patients, community health centers are likely to have longer wait times for an appointment and might not carry a woman’s preferred brand or type of contraception at all. “Other clinics don’t necessarily have night or weekend hours,” said Kami Geoffray, CEO of Women’s Health and Family Planning Association of Texas, a network of family planning providers. At Planned Parenthood, “you can pick up your birth control pills at the counter and get a same-day IUD insertion.” Guttmacher data shows that Planned Parenthood sites are more likely than community health centers to offer a wide range of contraceptive services and to have a pharmacy on site. Planned Parenthood clinics are also likelier than other health care providers to offer same-day appointments.

In Texas, getting women in the door also proved to be a challenge. Tara Haskell Ashmore was the CEO of a Planned Parenthood clinic in Lubbock, a college town in West Texas, when the cuts went into effect in 2013. She and her staff found a way to keep the lights on for a while — even merging with an adoption agency in an attempt to rebrand — but the clinic closed the next year. Now the chief financial officer of a rural health center outside Lubbock, she says her clinic is accepting new patients, but they haven’t seen an uptick in requests for family planning. “At Planned Parenthood we were seeing about 30 patients every day before the cuts, and now I think many of those women are going without care,” she said.

Research conducted in Texas after Planned Parenthood was defunded showed that the organization seemed to have an outsize impact. An analysis conducted by researchers at the University of Texas found that although only 23 of Texas’s 254 counties had a Planned Parenthood clinic before 2013, those clinics served 60 percent of the state’s low-income women of childbearing age. The study looked at pharmacy and medical claims for two kinds of long-acting contraception and found that in counties where a Planned Parenthood had been, the number of claims for these contraceptives declined by 36 percent in the first three months after the Texas Women’s Health Program went into effect. There was no similar decrease in counties without Planned Parenthood, suggesting that some women may have stopped receiving these contraceptives when their local clinics closed. Some Texas legislators criticized the study as “biased,” saying that the researchers should have looked at data from other sources.

In the U.S. House, Republicans’ Obamacare replacement bill would allocate additional funding for community health centers, but it’s unclear whether the influx of cash would be enough to cover services previously provided by Planned Parenthood. Rosenbaum said the abruptness of the transition could hurt some patients: Planned Parenthood would lose funding as soon as the bill became law, but community health centers couldn’t be ready immediately. Compounding this challenge is the fact that other proposed changes to the Affordable Care Act — like the eventual freezing of new enrollment in Medicaid expansion and changes in health insurance subsidies — seem likely to result in more people without insurance, broadening the pool of women the community health centers would need to serve.

In Iowa, Norris is concerned about where she can refer her patients if the local Planned Parenthood closes or scales back. “My biggest frustration is that lawmakers don’t seem to be listening to the people on the ground level,” she said. “We just don’t have the resources here in Iowa to replace what Planned Parenthood is offering my patients.”