Labour MP Gloria De Piero has announced she will not stand at the next general election as she criticised the party's "lack of tolerance".
The shadow justice minister has spent more than nine years representing the Ashfield constituency but told local members that she did not know if she could give them "the commitment you deserve for what could be a further eight years".
In comments carried on her website, the MP said a "lack of tolerance for different viewpoints in the Labour Party frankly worries me".
"We have to have respect for each other, even if we disagree, because we are all part of this party," she added.
"This party is about a set of values not any individual and we would all do well to remember that.
"And while I'm at it, and it doesn't happen in Ashfield, but when I hear people being called right-wing in the Labour Party I find it utterly offensive.
"We are all left-wingers in this party – that is why we joined the Labour Party," she said.