WATCH: Elton John’s Powerful Message: ‘This Congress Can End AIDS’

Best known for singing award-winning pop songs and anthems, Sir Elton John used his voice instead this week to urge the U.S. Senate to fund AIDS and HIV research and treatment at levels that will end a crisis more than three decades old.

"This Congress indeed has the power to end AIDS," said John during a Senate Appropriations Committee hearing. "There is a window of opportunity before us -- a window through which we can very clearly see the end of AIDS -- within my lifetime. We cannot afford to let that window close."

John talked about his AIDS foundation's efforts -- which have raised millions -- and pushed Congress to continue its own funding toward combating the disease until it is completely eradicated.

"This is the most powerful legislative body in the world," reminded John.

The first time he testified before Congress, in April 2002, only 50,000 of the nearly 30 million people living with HIV and AIDS in sub-Saharan Africa had access to antiretroviral medicine. Testifying once again on Thursday, he said things had improved significantly.

"Thanks to the unprecedented actions of Congress, an HIV-positive mother in South Africa can give birth to a healthy, HIV-free baby who she can live to raise," he said. "Thanks to the generosity of the American people, 9.4 million men, women and children have access to life-saving antiretroviral treatment."

But John also warned that if efforts are rolled back because of funding cuts or diverted attention, then the disease could "once again become a ruthless pandemic with disastrous and far-reaching consequences."

John explained to the senators how he had transformed himself from hit musician to one of the world's leading AIDS activists.

"You have to remember I'm British and I came over here in 1970," John said. "This country gave me everything as a professional musician, and it's given me everything to me as a human being. And the strength and the willingness to help people in the rest of the world has touched me so much."

John, 68, said he was inspired by Ryan White, the U.S. teenager who became a rallying figure in the late 1980s and early 1990s over changing the approach to combatting the AIDS epidemic. As The Advocate reported, John wrote to White. And White didn't hold back.

"It was Ryan White who pointed out to me that my life was in complete disorder," John said. "I was a drug addict. I was a self-obsessed asshole. Excuse me."

The senators and audience members laughed it off, as did his fellow panelist, Pastor Rick Warren.

Watch an exceprt of John's testimony below:

Watch the full hearing provided by C-SPAN: