Kris Jenner is reportedly "jealous" of Caitlyn Jenner's fame and success.
The 'Keeping Up With The Kardashians' star is reportedly furious that her ex-partner - who was known as Bruce Jenner before undergoing a gender transition - is more famous than she is.
A source said: "Caitlyn's instant rise to fame and support has everyone now focused solely on her and not on the Kardashians anymore. This was Kris' biggest fear.
"No one in the family was expecting Caitlyn to be as beautiful as she is. Everyone is shocked at how soft and natural she looks and, of course, Kris is just through the roof."
Kris is also believed to be devastated she is no longer the alpha female of the family.
An insider added to RadarOnline.com: "Already Caitlyn is more beautiful than Kris and more beloved by fans, and this has Kris spinning out in her head.
"Kris knows that she is no longer the 'momager with the most' and this drives her absolutely nuts!"
Meanwhile, Kris' younger sister Karen Houghton has admitted it "must be hard" for the 59-year-old television personality.
She said: "I don't know how Kris is doing. Poor thing. I hope Kris is okay because it must be hard."