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As far as storylines go, PEPFAR has had it pretty good so far. Since George W. Bush first introduced the President's Emergency Plan for AIDS Relief in 2003, the program has been able to swing around impressive credentials: more than 2 million people in 15 focus countries have started on antiretroviral treatment and more than 10 million have been supported with overall care. Thanks to the program's promising results, Congress raised the budget of PEPFAR by $4 billion over the course of its existence. With $6.7 billion to its name, PEPFAR is now the biggest public-health initiative in the world.

But after years of steady gains in funding, health experts say PEPFAR's funding will likely flatline under the Obama administration. At the same time, they expect the gap between the...