The lucrative annual deal would be in the same league as those signed by Lopez on American Idol and Spears' former fellow Mouseketeer Aguilera on The Voice.
After the firing of judges Paula Abdul and Nicole Scherzinger and host Steve Jones following the disappointing first season of the FOX competition show, the source says the show needs Spears' star power "badly . . .You can't have Idol with J Lo and Voice with Xtina and have X-factor with, um, Paula Abdul?"
An insider previously told Us that head judge and executive producer Simon Cowell balked at hiring Spears because he was "worried she won't be able to deliver good advice, and he's afraid contestants won't take her seriously."