Amidst the marching bands, bunting and banners of the annual Durham Miners Gala, the RMT general secretary accused the Labour leader of showing unions contempt and "dancing to the tune of Tony Blair" following plans to end the automatic affiliation of union members to the party.
Although the transport union was expelled from the party in 2004 for allowing Scottish branches to affiliate to other political parties, Crow claimed the shake-up announced earlier this week was an attempt to "hack away at the last remaining shreds of influence held by those who created the party".
At the Gala, he will attempt to rally support for a "new party of labour" to take on the "anti-worker" agenda of the three main Westminster political parties.
Last year Miliband became the first Labour leader in more than two decades to address the gala, also known as The Big Meeting, but will not attend this year.
Speaking ahead of the event, Crow said: "Over the past week 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.
"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.
"RMT was expelled from the Labour Party almost a decade ago and in that time we have actually increased our political influence as we have had the freedom to back candidates and parties who demonstrate clear support for this trade union and its policies.
"If others now join us after the contempt that they have been shown by Ed Miliband then together we have a world to win. This is a moment of huge opportunity for all those sick and tired of Labour's embrace of pro-business, pro-EU, neo-liberal policies and we should seize it with both hands.
"While this rotten ConDem Government seeks to impose punitive charges on anyone seeking justice at the employment tribunal from this summer the Labour Party have said nothing. The whole programme of Labour now is to try and sneak into government by default on the basis of a manifesto that could trade under the title 'carry on cutting'. Our job is not to prop up the political class behind this racket, our job is to sweep it away.
"With the latest assault by Labour on the unions 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. The time for the alternative party of labour is now."
Miliband launched plans for significant reform of the Labour Party's relations with the trade unions earlier this week - a move Blair hailed as ''a real act of leadership''.
The measures were designed to draw a line under the biggest crisis of Miliband's leadership, sparked by claims that Unite tried to fix the selection of Labour's general election candidate in Falkirk by packing the constituency with 100 or more of its own members, some of them without their knowledge.
An internal party report on the allegations has been handed to police.
Miliband said events in Falkirk represented ''part of the death throes of the old politics'', and he hoped to usher in an ''open, transparent and trusted'' system which would engage more union members directly in the party.
Rather than being automatically affiliated to Labour unless they opt out of their union's political levy, union members should be asked to make an active decision to join the party by opting in.
The explosive reaction expected from the unions did not materialise, however, as Unite general secretary Len McCluskey told how he was ''very comfortable'' with the proposals.