The next three weeks in Brazil could see the dirtiest, most divisive campaigning in the country's democratic history as two candidates in the presidential election slug it out to the run-off.

With 94 percent of the votes in the first round counted, far-right candidate Jair Bolsonaro came in first place with a resounding 46.93 percent.  Former Sao Paulo mayor Fernando Haddad of the Leftist Workers Party (PT) won 28 percent of the vote. 

"It's going to be a horrible campaign in the second round," said Monica de Bolle, the director of Latin American Studies at Johns Hopkins University to the Guardian newspaper.  "It's going to be one side smearing the other."

"We need to approach this with a sense of responsibility. We want to unite the democrats of this country, to reduce inequality and to achieve social justice," he told his cheering supporters.

Crime and corruption are rampant in Brazil, and the murder rate hit a record high last year.  Voters disgusted with the breakdown in institutions are tuned in to Bolsonaro's tough guy routine; he wants to restore the death penalty, allow police to torture suspects, and relax personal gun ownership laws.

"This idea that Bolsonaro can save the country and make it safe for people to walk on the streets at night and tend the corruption in Brasilia and make a dent in 13 million unemployed - that's an idea most Brazilians now seem to have bought," said Brian Winter, the editor-in-chief of Americas Quarterly."

Bolsonaro has in recent days attempted to shift his image to a more even-tempered candidate who would rule for all Brazil's 208 million citizens regardless of their skin-colour or faith.  This belies decades of controversial statements, which include racist vitriol hurled at minority communities, homophobia, and misogyny.  He has also attacked Democracy itself, praising the murderous, CIA-backed fascist dictatorship of 1964-1985 and suggesting the country should go back to military rule.  Last month Bolsonaro called for his left-wing political opponents to be shot.

Haddad's path to victory seems insurmountable.  He'll have to increase his appeal to win every Brazilian who voted for the minor parties, imploring them to choose Democracy.

"We need to approach this with a sense of responsibility" Hadded told supporters, "We want to unite the democrats of this country, to reduce inequality and to achieve social justice."