Brazil's national statistics institute said today that GDP shrank 0.6 per cent in the second quarter and revised its formerly positive growth estimate for the first quarter down to -0.2 per cent.
Coming ahead of October presidential and general elections, the figures will damage already low industrial and consumer confidence in what once was a fast-growing regional powerhouse.
And the contraction comes with Rousseff locked in a tough fight to win re-election, as the latest polls show a major surge in support for Marina Silva, challenging her from the left.
She had been Campos' running mate and took the reigns of his campaign.
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Polls this week show her defeating Rousseff in an October 26 run-off, although the latter remains favourite to top first round voting on October 5.
"The data are likely to be seized upon by Dilma Rousseff's challengers in the presidential race to attack her poor record on growth and inflation," said Robert Wood, Brazil analyst for the Economist Intelligence Unit.
Margarida Gutierrez, an economics professor at Rio University, warned 2015 would be tough.
"Brazilian growth has been slowing since 2011 owing to the great uncertainty surrounding economic policy and large degree of state intervention," Gutierrez told AFP.
"This year brings additional uncertainties -- the elections, the risk of electricity rationing and adjustments which will have to be made in 2015," she said.