Why did polls go wrong in the Brazilian presidential election?

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to me first round From Sunday’s presidential election in Brazil, outgoing President Jair Bolsonaro achieved a surprising result: He received 43.2 percent of the vote, much higher than polls had predicted, and forced out his main rival, the former leftist president and leader of the Democratic Republic of the Congo. Labor Party (PT) Luiz Inacio Lula da Silva, to go to the polls (Lula won 48.4 percent). Pre-election polls have given Monday much further: The most reliable poll, from the Datafolha Institute, gave Bolsonaro 36 percent.

The unexpected result of the first round could now have dire consequences for the result of the run-off on October 30, with Bolsonaro the most impetus candidate, although Lula is still several points ahead.

The failure of the elections was due to technical and political reasons. Among the technical reasons, they explained From the experts Le Monde, there was a “lack of data”. The last complete census of the Brazilian population, on which the survey’s calculations are based, dates back to 2010, and since then many things have changed: in particular, the population of evangelical Christians, who are on average strong supporters of Bolsonaro, has changed. It has grown a lot and may have been underestimated in statistical surveys.

There are also various political reasons: the extreme right-wing forces loyal to Bolsonaro, with the support of the president, have for some time now been campaigning to delegitimize various democratic institutions, such as the judiciary and the media. Among other things, Bolsonaro has on multiple occasions refused to guarantee his respect for the election result and has argued that all previous elections, including the one in which he was elected, have been rigged.

This campaign also had consequences for opinion polls, which were defined as “false” by Bolsonaro and his team because, in fact, it gave Lula a huge advantage. Many Bolsonaro supporters have refused for months to answer polls by phone, or responded with misinformation, which could reduce the accuracy of the readings.

At the same time, Lula’s election campaign was somewhat disappointing: many Brazilian voters voted for Lula mostly in opposition to the far right, and the former president was unable to stir up enthusiasm. that often accompanies Bolsonaro.

On Sunday in Brazil, there was not only a vote for the president, but also to elect 27 out of 81 senators, all 513 members of the House of Representatives and all 27 state governors. In this election, Bolsonaro’s surprising success was also tangible. Bolsonaro’s liberal party had the most votes in both the House and Senate (even if a majority was hard to come by) and its allies managed to occupy important states, such as Rio de Janeiro.

In this context, Bolsonaro can present himself not only as the candidate with the most momentum, given the recent electoral surprise, but also as the most stable, because the right already controls various institutions and has a good chance of controlling Parliament. Lula is still ahead in the polls, but many analysts say he will have to review much of his campaign between now and October 30, polling day.