As Keir Starmer faces the prospect of a leadership challenge, former Labour voters in a Birmingham constituency were last week feeling nervous about what could come next. A month ago, the group from Birmingham Yardley had very little good to say about the prime minister , comparing him to a rat or a donkey. They said they felt he had let them down. But the same constituents sounded distinctly worried about the idea of Labour MPs getting rid of Starmer when they gathered for a second focus group convened by More in Common in the week of the local elections. Bob, an engineering manager, summed up what several members felt. “I don’t know if it would be better off without him, because it’s like, at the moment things aren’t good, but things could always get worse and you don’t really know. “Sometimes it’s better the devil you know than whoever you don’t.…