Britney Spears has rejected a $10 million offer to judge the next season of The X Factor, TheWrap has learned. So the question is: How much is Fox going to have to pony up? Try $20 million. The singer rejected that offer three weeks ago and is instead thinking about an offer to become a resident performer at a Las Vegas hotel in the fall, a la Celine Dion. So here comes a game of chicken. Fox desperately needs a big name to announce on the judge’s panel of Simon Cowell’s show, now that NBC’s hit show The Voice will be competing with them in the fall. Spears’ camp wants $20 million.