Unite could disaffiliate from Labour as relations between Keir Starmer's party and its biggest donor are said to have deteriorated.
Insiders think Britain's most powerful union could cut ties with Labour within months if members force a special rules conference, as the rift between general secretary Sharon Graham and the party leader shows no sign of healing.
Grassroots anger over factional rows and a major clash between the two leading figures over the Coventry bin worker strike have seen tensions boil over in recent months.
