One of the biggest union affiliates to Labour is set to debate its future links with the party after an "unprecedented" number of branches raised concerns, it was revealed today.
The GMB said a quarter of motions to its annual conference in June related to the union's political stance in the wake of anger over statements by Labour leader Ed Miliband and shadow chancellor Ed Balls in support of some of the Government's austerity measures.
The two made speeches and gave interviews backing the cap on public sector pay in mid-January, two weeks before the closing date for motions to be submitted by GMB branches
The GMB's executive said in a statement: "The executive noted that over a quarter of motions to GMB congress from branches across the whole of the UK relate to the political stance of the union.
"The executive determined that the union's relations with the Labour party and what GMB members expect and want from the party will form a major plank in the debate at GMB congress in Brighton in June.
"The executive expressed concern and disappointment with recent statements made by senior party officials and registered their growing frustration at the lack of a cohesive policy to protect working people from the ravages of the Tory-led coalition Government."
A union source said the number of motions on links with Labour was "unprecedented" and ranged from stepping up efforts to "reclaim" Labour, to "walking away" from it.
The GMB gives Labour more than £2 million a year in affiliation fees and other funds, making it the third largest union donor to the party.
General secretary Paul Kenny wrote to his senior officials last month, saying Mr Balls' speech could have a "profound impact" on the union's relationship with Labour.
Dave Prentis, general secretary of Unison, accused Mr Miliband of "breathtaking naivete", saying there could be "unintended consequences".
Unite leader Len McCluskey warned that Mr Miliband was setting Labour on course for electoral "disaster" and undermining his own leadership.