"I do not believe one U.S. soldier being killed every day is success," said Dave Tiffany, who described himself as a full-time anti-war activist. He demanded to know from McCain "how long you want us to be there."

The two went back and forth several times, with McCain insisting that what matters most is ending American casualties, not their presence in Iraq. He said he would be fine with keeping troops in Iraq for decades as long as they weren't being harmed, similar to the arrangements that exist in South Korea, Japan and other countries.

"A thousand years. A million years. Ten million years," McCain said. "It depends on the arrangement we have with the Iraqi government."