The planned revival of a policy dating to Ronald Reagan’s presidency may finally present a way for President Donald Trump to fulfill his campaign promise to “defund” Planned Parenthood. Or at least to evict it from the federal family planning program, where it provides care to more than 40 percent of that program’s 4 million patients.

Congress last year failed to wipe out funding for Planned Parenthood, because the bill faced overwhelming Democratic objections and would not have received the 60 votes needed to pass in the Senate.

But the imposition of a slightly retooled version of a regulation, which was upheld by the Supreme Court in 1991 after a five-year fight, could potentially accomplish what Congress could not.

The rule now under review, a summary of which was unofficially provided to news reporters last week, would require facilities receiving federal family planning funds to be physically separate from those that perform abortion; would eliminate the requirement that women with unintended pregnancies be counseled on their full range of reproductive options; and would ban abortion referrals.

All those changes would particularly affect Planned Parenthood.

Planned Parenthood, which provides a broad array of reproductive health services to women and men, also provides abortion services using non-federal funds. Cutting off funding has been the top priority for anti-abortion groups, which supported candidate Trump.

“A win like this would immediately disentangle taxpayers from the abortion business and energize the grassroots as we head into the critical midterm elections,” Marjorie Dannenfelser, president of the anti-abortion Susan B. Anthony List, said in a statement.

In a conference call with reporters last week, Planned Parenthood officials said they would fight the new rules.

“We’ve been very clear, Planned Parenthood has an unwavering commitment to ensuring everyone has access to the full range of reproductive health care, and that includes abortion,” said Dawn Laguens, executive vice president of the Planned Parenthood Federation of America.

But when formally announcing the proposal Tuesday night, President Donald Trump said it would prevent American taxpayers from being “wrongfully forced to subsidize the abortion industry through Title X federal funding.”

Here is a guide to what the proposal could do and what it could mean for Planned Parenthood and the family planning program:

What Is Title X?

The federal family planning program, known as “Title Ten,” is named for its section in the federal Public Health Service Act. It became law in 1970, three years before the Supreme Court legalized abortion in Roe v Wade.

The original bill was sponsored by then Rep. George H.W. Bush (R-Texas) and signed into law by President Richard Nixon.

The program provides wellness exams and comprehensive contraceptive services, as well as screenings for cancer and sexually transmitted diseases for both women and men.

“We’ve been very clear, Planned Parenthood has an unwavering commitment to ensuring everyone has access to the full range of reproductive health care, and that includes abortion.”

In 2016, the most recent year for which statistics have been published, Title X served 4 million patients at just under 4,000 sites.

Title X patients are overwhelmingly young, female and low-income. An estimated 11 percent of Title X patients in 2016 were male; two-thirds of patients were under age 30; and nearly two-thirds had income below the federal poverty line.

What Is Planned Parenthood’s Relationship To Title X And Medicaid?

Planned Parenthood affiliates account for about 13 percent of total Title X sites but serve an estimated 40 percent of its patients. Only about half of Planned Parenthood affiliates perform abortions, although the organization in its entirety is the nation’s leading abortion provider.

Planned Parenthood also gets much more federal funding for services provided to patients on the Medicaid program (although not for abortion) than it does through Title X.

Eliminating Medicaid funding for Planned Parenthood has proven more difficult for lawmakers opposed to the organization because the federal Medicaid law includes the right for patients to select their providers. Changing that also would require a 60-vote majority in the Senate. So that particular line of funding is likely not at risk.

While opponents of federal funding for Planned Parenthood have said that other safety-net clinics could make up the difference if Planned Parenthood no longer participates in Title X, several studies have suggested that in many remote areas Planned Parenthood is the only provider of family planning services and the only provider that regularly stocks all methods of birth control.

Texas, Iowa and Missouri in recent years have stopped offering family planning services through a special Medicaid program to keep from funding Planned Parenthood. Texas is seeking a waiver from the Trump administration so that its program banning abortion providers could still receive federal funding. No decision has been made yet, federal officials said.

Why Is Planned Parenthood’s Involvement With Title X Controversial?

Even though Planned Parenthood cannot use federal funding for abortions, anti-abortion groups claim that federal funding is “fungible” and there is no way to ensure that some of the funding provided for other services does not cross-subsidize abortion services.

Planned Parenthood has also been a longtime public target for anti-abortion forces because it is such a visible provider and vocal proponent of legal abortion services.

In the early 1980s, the Reagan administration tried to separate the program from its federal funding by requiring parental permission for teens to obtain birth control. That was followed by efforts to eliminate abortion counseling.

Starting in 2011, undercover groups accused the organization of ignoring sex traffickers and selling fetal body parts. Planned Parenthood denies the allegations.

What Happened The Last Time An Administration Tried To Move Planned Parenthood Out Of Title X?

In 1987, the Reagan administration proposed what came to be known as the “gag rule.” The new rule being proposed by the Trump administration will be similar although not identical to the Reagan-era proposal.

The original gag rule would have forbidden Title X providers from abortion counseling or referring patients for abortions, required physical separation of Title X and abortion-providing facilities and forbidden recipients from using nonfederal funds for lobbying, distributing information or in any way advocating or encouraging abortion. (The Planned Parenthood Federation of America, the umbrella group for local affiliates, has a separate political and advocacy arm, the Planned Parenthood Action Fund.)

Those rules were the subject of heated congressional debate through most of the George H.W. Bush administration and were upheld in a 5-4 Supreme Court ruling in 1991, Rust v. Sullivan.

Even then, the gag rule did not go into effect because subsequent efforts to relax the rules somewhat to allow doctors (but not other health professionals) to counsel patients on the availability of abortion created another round of legal fights.

Eventually the rule was in effect for only about a month before it was again blocked by a U.S. appeals court. President Bill Clinton canceled the rules by executive order on his second day in office, and no other president tried to revive them until now.

How Is The Trump Administration’s Proposal Different From Earlier Rules?

The new rule, which will be open to comment for 60 days before being published in final form, would require physical separation of family planning and abortion facilities, repeal current counseling requirements, and ban abortion referrals.

One of the biggest differences, however, is that the new rules will not explicitly forbid abortion counseling by Title X providers.

But Planned Parenthood officials say that allowing counseling while banning referrals is a distinction without a difference.

Kashif Syed, a senior policy analyst for the organization, said: “Blocking doctors from telling a patient where they can get safe and legal care in this country is the definition of a gag rule.”

What Happens Next?

Planned Parenthood officials said they will not know if they will take legal action until they see the final language of the rule after the comment period. But they say they do plan to use the regulatory process to fight the changes that have been made public so far.

KHN’s coverage of women’s health care issues is supported in part by The David and Lucile Packard Foundation.

This story was written by Julie Rovner and contributed by Kaiser Health News, a national health policy news service that is an editorially independent part of the Henry J. Kaiser Family Foundation, a nonprofit, nonpartisan health policy research and communication organization not affiliated with Kaiser Permanente.