"What a beautiful voice, what a wonderful singer," Fergie tells ET. "She's amazing. I think she could definitely have a huge career. Her voice is lovely."
Jesse McCartney talks to ET about collaborating with OneRepublic front man Ryan Tedder to write Leona Lewis' hit song "Bleeding Love," but he also gushed about the breakout "Britain's Got Talent" star.
"I think she's amazing," he says. "Those are always the best success stories. And Simon Cowell always says it. He says on his show, 'It's fun to bring the most unassuming person up to the stage and hear something amazing come out of them.' It's really special."
The ASCAP Pop Music Awards honors the songwriters and publishers of ASCAP's most performed pop songs of 2008, watch the video to hear more from the talented music stars.