Union boss Bob Crow will seek to exploit Labour wranglings with trade unions by urging the movement to break ties with Ed Miliband and create a party that "speaks for working people".
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 today's Durham Miners Gala, one of the country's most traditional trade union events, 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.
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Downpours keeping us on our toes today
The M20 in Kent has been closed in both directions after a pedestrian bridge allegedly collapsed on the motorway on Saturday.
The AA have warned of traffic jams and urged people to carry extra water in their vehicles because of the warm weather.