Kris Jenner is refusing to allow Caitlyn Jenner on 'Keeping Up with the Kardashians'.

The 59-year-old star has vowed not to let her ex return to the reality show after she launched her own show 'I Am Cait', as she is still ''bitter'' about their split and the way Caitlyn spoke about her during her transition.

An insider revealed: ''Despite all the fanfare, the show's doing terribly in the US ratings. Caitlyn's beyond disappointed and so are her bosses. They initially commissioned eight episodes, but everyone was sure it would get picked up for a full 20-episode series like 'KUWTK'. That's very unlikely now.

''Cait wants to use her profile to help improve transgender rights, so she's been begging Kris to let her return to 'KUWTK'. But Kris has said in no uncertain terms the answer is no.

''Kris is so bitter over everything that's happened that she refuses point blank.''

In a desperate plea to save 'I Am Cait' and to remain in the public eye, Caitlyn has turned to stepdaughter Kim Kardashian West and her siblings to help persuade Kris to reconsider, although they have so far been unsuccessful and the 65-year-old star is scared her show might be axed.

The source continued: ''But the girls can see how upset Caitlyn is that viewers haven't responded to her show. She's taking it very personally as she was seeking acceptance from the public and she feels everyone's turning their back on her.''

And despite reuniting at their youngest daughter Kylie Jenner's 18th birthday party, Kris has remained firm about her decision.

The insider told Now magazine: ''Kylie wanted it to be a happy family occasion. Kris agreed to put her feelings aside for her sake and she and Caitlyn were all smiles and hugs. But deep down, she hasn't changed her mind about having Caitlyn on the show.''