Bob Crow, the rail union leader, is to call for an alternative "party of labour" to challenge the Tories, Labour and Lib Dems.
The general secretary of the Rail Maritime and Transport union, will tell a rally of activists that political representation of workers stands at a "crossroads" in the wake of the decision of the GMB to slash its affiliation funds to Labour by more than £1 million.
He will say: "Millions of working people are sick and tired of being treated as voting fodder by Labour," and add that a party needs to rise up to challenge the most brutal austerity measures "in a generation".
Speaking ahead of the TUC event in Bournemouth, he said: "Over the past two months we have seen Ed Miliband dancing to the tune of Tony Blair and the rest of the New Labour conspirators as he seeks to hack away at the last remaining shreds of influence held by those who created the Party that he leads, the trade unions.
"RMT's message is simple. If others want to stick around and be insulted by those whose only interest is our money and not our ideas then that's a matter for them, for the rest, there is a whole world of opportunity outside the constraints of the Labour Party and RMT would urge them to embrace it and join us in this new political project."
Mr Crow said that since being expelled from Labour a decade ago, the RMT has increased its political influence by backing candidates and parties demonstrating support for its policies.
He added: "Millions of working people are sick and tired of being treated as voting fodder by Labour and the time is right to start building an alternative political party that speaks for the working people and the working class communities that find themselves under the most brutal attack from cuts and austerity in a generation.
"Clinging to the wreckage of a Labour party that didn't lift a finger to repeal the anti-union laws despite 13 years in power is a complete waste of time."