Trade unions know a thing or two about taking nothing for granted. After years of decline following the introduction of anti-union laws by Margaret Thatcher in the 80s, overall membership figures are going up again.
Unions have achieved this by fine-tuning their relevance to members, but Tony Blair has failed to take a leaf out of the same book, ignoring calls to make policies more relevant to the party's traditional support.
Instead, he has increasingly alienated Labour's natural allies by pushing through controversial public sector reforms. This has happened over the heads of trade unionists, many of whom work in the public sector.
The scale of the difference between union hopes and government policy were dramatically illustrated when Unison pulled funding and practical support for the local elections earlier this year.
Officials said the union was in an impossible position, in dispute with the government over proposals to introduce early changes to the local government pension scheme.
Many union leaders feel Labour has lost direction - but can Gordon Brown turn things around, and should he count on union members voting for him in a leadership race?
Mr Brown's decision last year to publicly align his future policies with those of Mr Blair brought dissatisfaction in union ranks. Already, the chancellor is responsible for a number of policies to provoke union ire, including ploughing on with the private finance initiative to build new schools and hospitals.
Because affiliated trade union members will have a say in the outcome of the leadership race, Mr Brown should take nothing for granted, and other contenders could split the union vote.
The leftwing MP John McDonnell, who yesterday launched his leadership bid, is seen as a friend of the union movement and was behind a high-profile rally against the privatisation of public services earlier this year.
By the time Mr Blair steps down, other contenders who could turn union heads may have joined the race, including the education minister Alan Johnson, a former trade union secretary, who has been tipped to run.
He has both cabinet and trade union experience, but - unlike Mr McDonnell - is a Blairite and helped persuade unions to accept the abolition of clause four.
Nevertheless, it seems clear that, if it's policies that count, Mr Brown's backing by unions is not assured.
