Allegations of a dirty tricks campaign on WhatsApp dominated Brazil's presidential election race on Thursday, turning attention to social media manipulation following abuses uncovered in the last US election and Britain's Brexit referendum.
Trailing leftist candidate Fernando Haddad accused the far-right frontrunner, Jair Bolsonaro, of "illegal" electoral tactics after a report that companies were poised to unleash a flood of WhatsApp messages attacking him and his Workers Party.
Bolsonaro denied the allegation, tweeting that the Haddad's Workers Party "isn't being hurt by fake news, but by the TRUTH."
The exchange happened 10 days before a run-off election that polls predict Bolsonaro -- a bluff, internet-savvy, pro-gun polemicist often compared to US President Donald Trump -- will likely win comfortably.
Ordinary Brazilians told AFP they got much of their election information through WhatsApp. They said some in their families or entourage swallowed some misinformation, but denied they themselves were being influenced.
"We get a lot of news, even false news, but some true, about politics but I don't think it changes very much in terms of making decisions," said Ana Clara Valle, a 27-year-old engineer in Rio.
She said she was voting for Bolsonaro because of his Catholic, pro-family stance, not because of any "extreme right" sensibility.
Andre de Souza, a 35-year-old lawyer leaning toward voting for Bolsonaro, said he receives around 500 WhatsApp messages a day for and against both candidates.
The rumors and false information "don't make a difference to me," he said, but added: "My mother received a WhatsApp message saying Bolsonaro was doing away with (mandatory) end-of-year salary payments, and she believed it!"
- 'Slander' -
Haddad made his accusation after Brazil's widest circulation newspaper, Folha de Sao Paulo, reported it had discovered contracts worth up to $3.2 million each for companies to send out bulk WhatsApp messages attacking the Workers Party.
"We have identified a campaign of slander and defamation via WhatsApp and, given the mass of messages, we know that there was dirty money behind it, because it wasn't registered with the Supreme Electoral Tribunal," Haddad told a media conference in Sao Paulo.
Bolsonaro's lawyer, Tiago Ayres, told the financial daily Valor there was no evidence of any connection between the companies mentioned by Folha de Sao Paulo and Bolsonaro's campaign.
The row shone a light on an issue that has become a pressing one in democracies: the organized abuse of social media to sway public opinion in countries.
Facebook -- which owns WhatsApp, as well as popular image-based network Instagram -- is the most prominent company that has come under scrutiny, though Twitter has also come in for criticism.
The platforms have made an effort to clean up who uses their services after evidence of Russian interference in the 2016 US election that saw Trump triumph, and accusations Facebook allowed user data to be harvested to bolster the campaign the same year for Britain to leave the European Union.
Facebook has also shut down disinformation pages traced to campaigns believed to have ties to Iran's state-owned media and to Russian military intelligence services.
Seeking a debate
There is no evidence of foreign interference online in Brazil's election.
The director of major polling firm Datafolha, Mauro Paulinho, said on Twitter that his company had detected "some shifts" in public opinion just before the first round of the election on October 7, which Bolsonaro won handily.
"Technical and factual observations" were made, he said, without drawing any conclusions.
There are 120 million WhatsApp user accounts in Brazil, whose population is 210 million. The app works as a popular social network for friends, families and work colleagues.
Both Haddad and Bolsonaro are the subject of memes, cartoons and slogans circulating online in Brazil.
Haddad, a former education minister and ex-mayor of Sao Paulo, has repeatedly tried to draw Bolsonaro into televised debates on policies.
The leftist candidate has an academic background he believes would give him an advantage if the exchanges moved away from the one-line quips and insults that characterize most social media communications.
But Bolsonaro, who skipped early debates because he was recovering from a knife stab wound after being attacked by a lone assailant while campaigning last month, has thus far shown little inclination to go head-to-head with Haddad.