South Africa's largest trade union says it will no longer back the ruling African National Congress, in a tectonic shift in the country's politics ahead of elections next year.
The National Union of Metalworkers of South Africa (Numsa) announced the break at a special congress of members.
"Numsa as an organisation will neither endorse nor support the ANC or any other party in 2014," said leader Irvin Jim, who also called on President Jacob Zuma to resign.
The announcement could spell trouble for South Africa's ruling "tripartite" alliance, which has helped the ANC coast to victory in every elections since the end of white rule in 1994.
The ANC has entered each election with vital logistic and political support from the trade union umbrella group Cosatu - of which Numsa is the biggest member - and the Communist Party.
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With more than 300,000 members, Numsa is an influential source of votes, cash and grassroots organisation in South African politics.
Many members of Numsa are also members of the ANC.
On Friday Numsa also called on Zuma to step down and for Cosatu as a whole to withdraw its support for the ANC.
"The congress called on President Jacob Zuma to resign with immediate effect because of his administration's pursuit of neo-liberal policies... steeped in corruption, patronage and nepotism," said Jim.
He also suggested a new political party could be created.
"The time for looking for an alternative has arrived," he told hundreds of cheering members at the end of a four-day congress, floating the idea of establishing a new socialist party.
"Numsa will explore the establishment of a Movement for Socialism as the working class needs a political organisation committed to its policies and actions."
He said the working class had been used as "voting fodder" through the alliance which only operates around election.
"Swelling the ranks has merely resulted in delivering more working class victims like lambs to the slaughter by the ANC's bourgeois leadership."
The union also called for a parallel investigation into the police killing of 34 miners at Marikana, which is already being probed by a government appointed commission.
The ANC is still expected to win next year's vote, but with Zuma under fire and unemployment high the party's share of the vote could drop to less than 60 per cent.
