Some of Washington’s most powerful people delivered to the 19th International AIDS Conference pretty much the same message: Fighting AIDS is a good investment that is getting better every year, but current spending isn’t enough to end the epidemic.

Whether the world’s richer countries, and especially the United States, will decide to increase spending or alternatively wring more from current investment is a matter of much discussion among the 25,000 researchers, clinicians and activists here through Friday.

The United States spends $22 billion a year domestically on prevention and treatment of AIDS, up $2.5 billion since the start of the Obama administration. It spends $6.6 billion a year on AIDS-related activities overseas — more than six times total U.S. spending on global health in 2000.

All told, $17 billion is spent each year on AIDS in the developing world, where 8 million people are on life-extending antiretroviral drugs. To get 15 million people on those drugs by 2015 — the current goal — donor and recipient countries will together have to come up with $24 billion a year.

“Why can we continue to pour $100 billion a year into Afghanistan but we can’t find a quarter of that to end a global pandemic?” asked Sen. John F. Kerry (D-Mass.) in one session. “This is precisely the moment we need to invest more, so that past investments are not lost and we don’t slide back.”

Sen. Lindsey O. Graham (R-S.C.) noted that Congress’s appropriation for HIV/AIDS this year exceeded President Obama’s request. “To the American taxpayer, your money is going to a good cause,” he said.

Graham praised George W. Bush, whose President’s Emergency Plan for AIDS Relief (PEPFAR) launched this country’s big-ticket international AIDS spending in 2003. Of such far-flung spending he said, “It’s okay for Republicans to get involved in this. This is a worthy cause for both parties.”

Secretary of State Hillary Clinton got a standing ovation when she addressed 7,000 people in the conference center’s largest hall in a morning plenary session.

She reinforced her call in November for an “AIDS-free generation” — a phrase that’s becoming a battle cry. She described it as a time when there would be no child born with the virus, young adults would have a significantly lower risk of becoming infected and life-extending antiretroviral treatment would be available for anyone who needs it.

“HIV may be with us into the future until we finally achieve a cure [and] a vaccine, but the disease that HIV causes need not be with us,” she said.

She said three interventions will be necessary: Antiretroviral drugs need to be used much more widely so that infected people have little chance of transmitting HIV to others — called “treatment as prevention.” Circumcision, which reduces female-to-male transmission, must be practiced more widely. All pregnant HIV-infected women need to be treated with antiretrovirals in order to protect their babies during birth and breast-feeding.

Clinton’s address was also an opportunity for her to detail renewed American financial investments through PEPFAR and the Global Fund to Fight AIDS, Tuberculosis and Malaria.

She said the United States has spent $1 billion in recent years to prevent mother-to-child transmission, and that $80 million more will be spent to bring infected pregnant women into long-term care. She also said that PEPFAR will devote an additional $40 million to circumcise about 500,000 men and boys in South Africa. An additional $15 million will go for “implementation research.”

She said that Zambia, one of PEPFAR’s 12 “focus countries” in Africa, cut the number of new infections in half from 2009 to 2011.

“If you’re not getting excited about this, please raise your hand and I will send somebody to check your pulse,” she said to laughter and applause in the cavernous hall.

Clinton also urged world leaders to address government corruption in the procurement and delivery of drugs, to protect sex workers and injection drug users, and to work toward paying for the AIDS response in their own countries.

She acknowledged that none of her listeners needed convincing.

“One could say I am preaching to the choir,” she said. “But right now, I think we need a little preaching to the choir . . . while I want to reaffirm my government’s commitment, I’m also here to boost yours.”

In one session, philanthropist and Microsoft co-founder Bill Gates chatted with a group of people that included Jim Yong Kim, a physician who just assumed the presidency of the World Bank, and Eric Goosby, a physician who heads PEPFAR.

Gates disputed the assertion made by many people that the tools for ending the epidemic already exist. The main one lacking is a vaccine, but also important and missing are woman-controlled means to prevent infection, such as a vaginal microbicide.

“No one should think that we have the tools yet. But we will have the tools if we stay the course,” he said. He described some of the Bill & Melinda Gates Foundation’s recent investments fighting AIDS, which have totaled $4 billion.

Kim, who co-founded Partners in Health, which has worked with the poor in Haiti, Peru and Rwanda, said that “it’s only in places where you have financial constraints that you have truly breakthrough innovations” in delivering services like medical care. He said that procurement methods and systems put in place in the ramp-up of AIDS programs in low-income countries in the past few years will teach useful lessons to other government sectors, such as education.

“At the World Bank we’re going to work on that ‘systems science’ with great focus,” he said.

Goosby said that in the early years of PEPFAR, U.S.-sponsored programs often worked in parallel with those financed by the Global Fund and national governments, creating a lot of duplication. There’s much less of that now, he said. PEPFAR has also been able to make its money go much further by buying generic drugs almost exclusively and shipping them more cheaply. The cost of treating an HIV-infected patient today is half what it was in 2008.

“But at some point we will need to inject more resources,” Goosby said. “I don’t want to give the impression that we have enough.”

In a meeting that discussed how public-private partnerships around the world can deliver innovative programs for AIDS care and advocacy, Elton John commended scientists’ progress but urged activists to continue demanding compassion toward HIV-infected populations who remain most vulnerable — including drug addicts, prisoners and sex workers.

“The AIDS disease is caused by a virus, but the AIDS epidemic is not,” he said. “The AIDS epidemic is fueled by stigma, by hate, by misinformation, by ignorance [and] by indifference.”

John also echoed Clinton’s call for an “AIDS-free generation.”

The end of AIDS “is not a mirage,” he said. “It’s real — it’s very, very real. But it’s going to take a lot more compassion to get us there . . . a hell of a lot more.”