Britain's biggest union could cut ties with the Labour party unless the next leader acts as the "voice of ordinary people", Unite boss Len McCluskey has warned.
Mr McCluskey said it was essential that the "correct" choice was made as the party decides who should succeed Ed Miliband after its devastating election defeat.
Mr McCluskey added that if the next person to lead the party failed to stem "disillusionment" among members of the union then it might rethink its affiliation which would result in Labour losing millions of pounds in funding.
The comments came as tensions over Labour's future direction emerged with Jon Cruddas suggesting the party needs to "fundamentally rethink" its vision.
Jim Murphy announced yesterday he was quitting as leader in Scotland and delivered a parting shot at Mr McCluskey, in which he said that the union boss should not be allowed to choose the party's next leader.
But speaking on BBC Radio 5 Live show Pienaar's Politics, Mr McCluskey said he was being portrayed as a "bogeyman".
He added that in terms of Labour it was "essential that the correct leader emerges, and that there's a genuine debate about the direction we are going in".