For decades, the U.S. has bankrolled global efforts to fight the spread of AIDS, saving tens of millions of lives. Congress has extended the program on a bipartisan basis since President George W. Bush created it in 2003.

At least, until now. Congress is gridlocked on a bill that would reauthorize the program, known as PEPFAR. Lawmakers passed a spending deal on Saturday to avert a government shutdown for 45 days, but that legislation did not reauthorize the AIDS program.

Without reauthorization, parts of the program expired over the weekend. If Congress does not act soon, organizations that deliver lifesaving drug treatments and other forms of support to H.I.V. patients could have to curtail their work. And some specific measures could lose funding, including one that provides care for orphans and other vulnerable children.

“PEPFAR has been a shining example of a bipartisan commitment to addressing a global health issue,” my colleague Sheryl Gay Stolberg, who covers health policy, told me. “If it doesn’t get reauthorized, it will be an example of how Washington is so broken that it’s even abandoning its moral leadership in the world.”

Why is this happening? Abortion politics are largely to blame. Some of the health organizations that fight AIDS also provide abortion services, and Republicans do not want to subsidize those groups. Even if the money does not directly fund abortions, these critics worry that PEPFAR strengthens the groups that provide them. House Republicans passed a bill last week extending the program only for a year and with more anti-abortion restrictions.

Supporters, including some Republicans, want a five-year extension without any new anti-abortion language. Many worry that cutting off groups that also provide abortions would damage anti-AIDS efforts. In recent weeks, Bush — himself an opponent of abortion rights — lobbied for the program’s renewal.

Global success

There is no partisan dispute on one point: The AIDS relief program is a major public health success. It has saved 25 million lives, equivalent to the population of Australia. In some countries, it has helped reduce the rate of H.I.V. infections by half or more.

How? The program funds health care services in more than 50 countries. It has helped build clinics that distribute antiretroviral medications for H.I.V., which reduce the risk of developing AIDS and undercut the virus’s ability to spread. It has established testing centers to help catch the virus earlier. And it has encouraged other preventive measures, such as safer sex practices and circumcision.

The program is especially important in western and southern Africa. Many H.I.V. patients in these regions otherwise struggle to get treatment.

Nothing in the program directly funds abortions.

Critics’ argument is, in short, that money is fungible. Program partners may not use federal funds directly on abortions, but they may use the money to set aside other dollars that can then go to abortions. The critics want the program to stop supporting any group that provides abortion services.

But PEPFAR operates in many countries that lack basic health care infrastructure, so it cannot be all that picky in choosing partners. In some regions of the world, strict anti-abortion language could force the program to pull out because it would no longer be able to find a partner that meets its standards. More people would die from AIDS as a result.

What’s next

PEPFAR remains funded for now. But Congress has not passed a longer-term extension of the program, which requires a separate bill.

If Congress does not reauthorize the program, it could send a chilling message. For the first time in decades, the global fight against AIDS would no longer seem like a bipartisan priority. The program’s partners may start to wonder whether they can rely on the funding and if they should work with the U.S. on a now-politicized issue. “It would be a huge departure from the past,” said Jennifer Kates of KFF, a health policy organization.

For an AIDS fight that has saved so many people over the decades, those problems could over time translate to millions of preventable deaths.

Related: Women in poor places where H.I.V. is still very common often struggle to get preventive

medicine, The Economist writes.