By Julie Rovner, Kaiser Health News

If there’s anything congressional Republicans want to do more than “repeal and replace” the Affordable Care Act, it’s defund Planned Parenthood, which provides health care to women around the country. But Senate rules could prevent lawmakers from accomplishing both of those goals in the same bill, as they intend to do.

The American Health Care Act, passed by the House earlier this month to overhaul the federal health law, would bar funding under the Medicaid program for one year to any “prohibited entity” that “is primarily engaged in family planning services, reproductive health, and related medical care; and… provides for abortions” other than those for rape, incest, or to protect the life of the woman.

Although Planned Parenthood is not mentioned, it is clearly the target of the provision. On the other hand, the Senate parliamentarian could rule that the language does not qualify to be included in this specific bill.

The provision has mostly flown under the radar in recent debates about the bill. But defunding Planned Parenthood is a top priority for powerful anti-abortion groups counting on its inclusion as a condition to support the bill. Failure to pass the Senate would pose enormous political problems for the measure.

“Congress has the votes to get it done. There are no excuses for inaction,” warned Marjorie Dannenfelser, president of the Susan B. Anthony List, in a statement aimed at lawmakers in March.

Whether Congress truly has enough votes to pass the bill is unclear. Congress is using the “budget reconciliation” process for its health law overhaul because reconciliation bills cannot be filibustered in the Senate and require only a simple majority vote—rather than the typical 60—to pass. Republicans control 52 seats in the Senate.

Under Senate rules for reconciliation, any provision in the measure must primarily be aimed at affecting the federal budget, either adding to or subtracting from federal spending. Items for which spending is “merely incidental” to a broader purpose can be ordered dropped from the bill by the parliamentarian under the “Byrd Rule,” named for its author, Sen. Robert Byrd (D-WV), a longtime Senate leader who died in 2010.

In the past, policies related to abortion have been singled out as violating that rule. Robert Dove, who served as parliamentarian twice in Republican-controlled U.S. senates, said in a 2010 interview that he ruled an abortion ban out of order in a 1995 reconciliation bill because “it was my view that the provision was not there in order to save money. It was there to implement social policy.”

Republicans have defended the inclusion of the Planned Parenthood provision in the reconciliation bill. House Speaker Paul Ryan (R-WI), when defending the lack of anti-Planned Parenthood language in the spending bill that passed last week to keep the government running, said the measure “needs to be in the reconciliation bill—as it is—because that’s how you get it into law.”

Planned Parenthood gets an estimated 75 percent of its government support from the Medicaid program, mostly for birth control, sexually transmitted disease screening and treatment, and well-woman care. The language, if it becomes law, would have a major effect on the organization and its affiliates. The federal “Hyde Amendment” has for 40 years barred the use of federal funds for most abortions, but the fact that many Planned Parenthood affiliates offer separately funded abortion services has made the organization a longtime target of abortion opponents.

Defenders of the provision point out it is identical to language included in a 2015 budget bill that was vetoed by President Barack Obama.

“That same language already has a track record of success, passing Congress in 2015,” also under the Senate’s reconciliation rules, wrote Tony Perkins, president of the anti-abortion Family Research Council, in a blog post for supporters.

But passing parliamentary muster once “does not guarantee” the same language will be approved again, said Richard Kogan, a budget process expert at the Center on Budget and Policy Priorities, a Washington-based think tank. “A true precedent exists only when a point of order has been raised and the chair has made a ruling,” he said.

And while the language has not changed, circumstances around it have. For one thing, since 2015 the Congressional Budget Office has interpreted the language less broadly than it is written. “CBO expects that, according to those criteria, only Planned Parenthood Federation of America and its affiliates and clinics would be affected,” CBO said in its official estimate of the original House bill.

That would not, on its face, rule the language impermissible as part of the reconciliation bill. But supporters of Planned Parenthood said if lawmakers thought there was no potential problem, they would have simply named the organization in the bill, as in separate legislation introduced this year.

The CBO also lowered its estimate of how much the provision would save—from $235 million for a one-year defunding in 2015 to $156 million in 2017. The bill includes only a one-year ban on funding because CBO has estimated a permanent funding ban would actually cost money—as women who don’t get birth control get pregnant, have babies, and possibly end up qualifying for Medicaid.

In the end it will be up to Senate parliamentarian Elizabeth MacDonough to make the call. Typically, the parliamentarian hears both sides argue their case before making a decision on whether a provision is allowable or not.

Even if MacDonough approves the provision, it is still not smooth sailing in the Senate. At least three GOP senators—Susan Collins of Maine, Lisa Murkowski of Alaska, and Dean Heller of Nevada—have said they are uncomfortable with defunding Planned Parenthood.

“That is an important issue to me because I don’t think that low-income women should be denied their choice of health care providers for family planning, cancer screenings, for well-woman care,” Collins said Sunday on ABC.

Those three votes would, if the senators followed through, be enough to force the provision out in the Senate.

And if the bill went back to the House with no Planned Parenthood defunding, “it would be problematic, I believe, based on my conversations with my colleagues,” said Rep. Mark Meadows (R-NC), a leader of the House Freedom Caucus who helped negotiate the final language in the House bill.

Anti-abortion groups like Susan B. Anthony List are counting on the language staying in. “We urge the Senate to keep these non-negotiable provisions and quickly advance this bill to the President’s desk,” Dannenfelser, the group’s president, said in a statement.

Kaiser Health News, a nonprofit health newsroom whose stories appear in news outlets nationwide, is an editorially independent part of the Kaiser Family Foundation.