PMDB, Mr Barbalho last month responded with a demand that Congress should set up no fewer than three special committees to investigate his foe.

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Former president Jose Sarney, whose PMDB party is one of the biggest members of her coalition, was re-elected head of the senate for the fourth time.

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The PMDB's barons were already displeased with what they regarded as a meagre clutch of ministries and other important jobs in Ms Rousseff's government, but had hitherto toed the line.

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Lula wants Mr Sarney to swing the weight of the PMDB, and its patronage machine, behind Dilma Rousseff, the probable candidate of the ruling Workers' Party in the presidential election next year.

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PMDB, a large and amorphous centrist outfit.

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The resulting scandal caused Lula to lose interest in difficult tax and labour-law reforms in his second term and to forge an alliance with the PMDB, an agglomeration of regional barons with a voracious appetite for patronage and pork.

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On May 24th all but one of the 73 lower-house deputies of the catch-all Party of the Brazilian Democratic Movement (PMDB), the PT's main coalition partner, voted for an amendment to a new Forestry Code to grant an amnesty for illegal logging before 2008.

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