The leadership of one of Britain's biggest unions will no longer give cash to the Labour Party and will instead give donations direct to some MPs.
The GMB is the latest union to reconsider its historic ties to Labour
The GMB - which normally gives £750,000 to help Labour fight elections - will only back MPs and candidates who support the union's policies.
The move follows the Fire Brigade Union's decision to sever Labour ties.
A Labour spokesman said: "Any decision on a union's political fund is a matter for that union."
The spokesman stressed that unions had recently upped their affiliation fees and party funds were in a £2.6m operating surplus last year.
Working people's support?
He added: "Labour candidates will fight on a manifesto agreed by the Labour Party.
"We believe that a government which has created two million extra jobs, introduced the first ever national minimum wage and is busy improving the country's schools and hospitals deserves the support of working people."
There has been growing disquiet in the union movement over a number of issues including the war with Iraq, the role of private finance in the public sector and pensions.
The Rail, Maritime and Transport Union has been thrown out of Labour for deciding to back other parties.