Diane Abbott has accused Ed Miliband of favouring only politicians who "will literally read from the script", days after being dropped from the Labour front bench.
The former shadow health minister said she had been loyal to the Labour leader but that she was dropped in last week's reshuffle because she spoke on her own terms.
"I think he's been convinced that what you need in the run up to the general election is people who will literally read from the script," she told Sunday Politics on BBC1.
"Every weekend Labour party people are given a script, and they're expected to read from it. Even thought I was speaking party policy I wasn't speaking from the script.
"All summer long when other shadow cabinet members were bitching about him behind the scenes, I was loyal to him in public and private."
The Hackney North and Stoke Newington MP says she has no plans to run for London mayor, despite rumours to the contrary.
Fellow London MPs Sadiq Khan and David Lammy are considered front runners in the Labour fight to take on the Tories in City Hall.
Comedian and Labour campaigner Eddie Izzard said he plans to run in 2020.