Republican legislators have repeatedly tried to end federal funding for Planned Parenthood — questioning why the non-profit gets money from the government in the first place.

In the wake of sting videos taped inside Planned Parenthood clinics, Sen. Rand Paul (R-KY) promised to use "all legislative vehicles at his disposal" to force a vote defunding the organization. Sen. Ted Cruz (R-TX) made similar promises to file an amendment that would, according to the Hill, "eliminate all federal funding for Planned Parenthood."

Planned Parenthood receives more than $500 million annually in government funding, mostly through Medicaid and grants. Most of this money goes toward providing low-income women with family planning services like STD screening and contraceptive coverage. Planned Parenthood is, without a doubt, one of the largest providers in this space: Of the 6.7 million women who rely on public programs to pay for contraceptives, 2.4 million of them — 36 percent — do so at Planned Parenthood's 817 clinics across the country.

2.4 million women receive subsidized contraceptives at Planned Parenthood

If Congress did defund Planned Parenthood, it would be a huge blow to the group: About 40 percent of its budget comes from government grants, and much of that spending gets done on the federal level. Because Planned Parenthood is such a large provider in this space, it's hard to see other clinics stepping in to fill the gap that it would leave.

Planned Parenthood received $528.4 million in public funding last year

Just over 40 percent of Planned Parenthood's budget comes from government grants and reimbursements, the organization's most recent budget report shows. Between June 2013 and 2014, Planned Parenthood received $528.4 million in public funding, a big chunk of its $1.3 billion national budget.

That $528.4 million figure covers both state and federal funding, and Planned Parenthood does not publicly break out how much money it gets just from federal funding. The best estimate arguably comes from the Government Accountability Office, which estimated that Planned Parenthood received $105 million in federal funding in 2012.

There are two main ways Planned Parenthood receives public funds. One is through Medicaid, the public health insurance program that covers 71 million low-income Americans. Whenever a Medicaid patient has an appointment at a Planned Parenthood clinic, the nonprofit will bill the health plan for whatever services the patient uses.

The other source of funding is grants, largely through the Title X Family Planning Program — the only domestic grant program dedicated to family planning. Organizations like Planned Parenthood often use Title X grants to subsidize birth control, STD screenings, and other reproductive health services for low-income patients who may lack health insurance coverage.

Planned Parenthood receives Title X funds both directly from the federal government and from states, which will sometimes make the nonprofit's health center a subgrantee for the dollars they receive from the federal government.

Planned Parenthood uses federal funds to cover reproductive health services — but not abortions

Both Title X and Medicaid provide low- to middle-income women with financial assistance to cover family planning costs. Medicaid might, for example, reimburse Planned Parenthood when it provides a patient with an HPV vaccine. And a Planned Parenthood clinic could use Title X grants to subsidize the placement of an IUD, which can cost upward of $500 for an uninsured patient.

The exact family planning benefits that Medicaid covers varies from state to state. But generally, many states will cover contraceptives, STD screenings, HPV vaccines, and cancer screenings as well as sterilization and reversal procedures — and will reimburse Planned Parenthood when it is the provider.

Laws prohibit federal government funds from paying for abortions

Thirty-two states and the District of Columbia have Medicaid programs that will pay for abortions, although those health plans are barred from using federal dollars — and have to use the state's share of funding to pay for the procedure.

Title X often covers the same type of services as Medicaid, except for women who are not on the public program. One important difference: Title X funds are never available to be used for abortions, even in states where the Medicaid program covers the procedure.

Federal law expressly prohibits the use of Title X funds to pay for abortions — while abortion providers like Planned Parenthood can qualify for grants, the government requires that no federal dollars go toward the termination of pregnancies.

How would defunding Planned Parenthood work?

No legislation to defund Planned Parenthood has ever passed, so its a bit hard to know — and even how, exactly, Planned Parenthood would lose its fund varies in different legislative proposals.

Historically, when congressional Republicans have talked about "defunding Planned Parenthood," they've meant barring the group from receiving Title X funds.

This is the type of bill the House passed in 2011. It would have disallowed any abortion providers — Planned Parenthood clinics or otherwise — from getting Title X grant funds.

That type of bill would put a dent in Planned Parenthood's budget, but it would be far from ending the group's federal funding. They would still receive funding through Medicaid, a much larger program than Title X — and near certainly a bigger chunk of Planned Parenthood's budget.

Planned Parenthood does not provide a breakdown of its government funding, but separate data suggests it almost certainly gets way more public revenue from the Medicaid patients it sees. One analysis from the Guttmacher Institute shows that Medicaid, a program jointly funded by states and the federal government, pays for 75 percent of publicly funded family planning services in the United States — while Title X covers 10 percent.

In order to fully defund Planned Parenthood, Congress would need to pass a law that bars Medicaid from reimbursing its clinics for patient visits there. This type of amendment hasn't historically come up in congressional debates about cutting Planned Parenthood's budget, perhaps because it's a much more drastic move than proposing cuts to Planned Parenthood's Title X funding.