The GMB threatened last summer to end donations to 35 Labour MPs. But the warning has proved a damp squib with only five losing funding from the union.
The union, one of Britain’s “big three”, said in June last year that it would withdraw financial support from up to 35 MPs because they had failed to back traditional Labour policies.
The announcement was seen at the time as a sign of growing alienation of unions under Gordon Brown’s government.
But the GMB’s failure to implement the threat may raise scepticism over similar warnings.
Unison, the public sector union, said last week that it would cut its support for Labour unless the party stopped “biting the hand that feeds it”.
A spokesman for the GMB said it had threatened to withdraw funding from 35 MPs because they had been “marked out” for their lack of commitment to the union’s causes. He insisted the union would have followed through on its threat but had not needed to.
While six were removed last June, no more names followed. One of the six – Robert Blackman-Woods – was reinstated after talks with the GMB. Of the five who lost the funding, some dismissed it as negligible. Adrian Bailey, for example, said he received only about £90 a year from three GMB-affiliated delegates.
Last week Dave Prentis, general secretary of Unison, said there would be no more “blank cheques” for Labour and that payments to constituencies would be suspended. The union has halted constituency payments to 64 MPs worth £100,000 a year, although it will pay its membership subscriptions to Labour.
A spokeswoman said the cut to the MPs could be temporary but depended on Labour reversing its pro-market stance.
Mr Prentis said Unison would also withhold the £1m it would normally give Labour ahead of a general election unless it saw promises in the party manifesto of an end to creeping privatisation in the public sector.
The Communication Workers Union is, meanwhile, threatening to withdraw its funding over Labour plans to part-privatise Royal Mail, although it has not yet gone to a vote.
For Labour, a bigger threat is that its funding supply from the unions could wither because of the problems eroding membership levels.
One source from Unite, the biggest union in the country, said membership was likely to decline by 10 to 15 per cent this year as the recession hits employment levels. Unemployment is expected to rise from about 2m last year to about 3m next year.
For now that may not affect donation levels, given that most unions do not class all of their members as “affiliates”. This means they can absorb some loss of membership before having to cut their donations, but only temporarily.