Rio de Janeiro, Dhu-AlQa'dah 24, 1435, Sep 19, 2014, SPA -- The wave of support that turned environmentalist Marina Silva into a sudden favourite for the Brazilian presidency appears to be dissipating, with President Dilma Rousseff again the front runner, according to dpa. An opinion poll by the Datafolha institute published Friday in the Folha de Sao Paulo daily said the centre-left Rousseff would get 37 per cent of the votes. The elections are set for October 5. Silva's voter base has shrunk from 33 to 30 per cent since earlier this month, the poll said. Third-placed social democrat Aecio Neves was up two percentage points, on 17 per cent of the vote. If these results are confirmed at the ballot box, Rousseff and Silva - both former ministers in the government of former president Luiz Inacio Lula da Silva - would go into a face run-off on October 26. The poll says Silva would win that vote with 46 per cent, to Rousseff's 44 per cent. But the poll has a two-percentage-point margin of error. -- SPA 18:52 LOCAL TIME 15:52 GMT www.spa.gov.sa/w