Britney Spears before the first day of taping the second season of The X Factor auditions for which she is a judge on May 24, 2012 in Austin, Texas. Credit: Gary Miller/

Can Britney Spears handle the pressure of live TV?

As one of two new judges on The X Factor, the pop icon, 30, is off to a rocky start. "Doing X Factor may lead her back into meltdown territory," a source recently told Us Weekly. "She gets extremely nervous and anxious. She's hard on herself and not very confident."

Even positive developments like her engagement to Jason Trawick, 40, can send her over the edge. "For her, it's all an input as stress," the source explains. "This is a lot of change at once for Britney. She's coming undone."

To her credit, Spears -- who has sold more than 100 million records worldwide -- has slowly rebuilt her career since her 10-day stay in the UCLA Medical Center psychiatric ward in early 2008. Her two post-crisis albums, 2008's Circus and 2011's Femme Fatale, went platinum, and she spent seven months on tour promoting the latter.

"Jason and Britney's family wouldn't let her do X Factor if she couldn't handle it," an insider countered. "At first they weren't going to let her because she couldn't do live TV -- they didn't know what she would say. But they went over it with Britney, and they trust her."

X Factor creator and fellow judge Simon Cowell, 52, isn't worried about Spears' unpredictability. "The network is using Christina Aguilera on The Voice as an argument for her," an industry insider told Us. "They're saying the show needs a bankable pop star who will get viewers watching, whether they think she's ridiculous of they love her. It's definitely about tapping into Spears' fan base."

Despite her nerves, Spears "wants to do a good job," a source insists. "There is always apprehension about something you haven't done before, but she's looking forward to proving all the doubters wrong."