Brazilians will vote in their general elections on Sunday, with a polarising candidate positioned as the front-runner.
Jair Bolsonaro has been compared to Donald Trump, but there are fears he is far more extreme.
Time magazine Brazil correspondent Matt Sandy told Newshub the former military officer has been a lone far-right voice for years.
"Calling for the return of the dictatorship, at different times he's called for genocide and torture, he's defended extrajudicial killings."
A military government ruled Brazil from 1964 to 1985. Mr Bolsonaro has in the past said the dictatorship "led to a more sustainable and prosperous" Brazil, and called it a "glorious" time for the country. He said it was a mistake that the regime only tortured opponents instead of killing them.
In the 1990s Mr Bolsonaro said if he was elected President, he would shut down congress.
Brazil's Workers' Party compared Mr Bolsonaro to Nazi dictator Adolf Hitler in a campaign video. In an opinion piece published by magazine Foreign Policy, he was compared to Nazi propaganda chief Joseph Goebbels.
Last year he was found guilty of incitement to rape and fined, after telling a fellow politician she wasn't "worthy" of being raped.
In 2011 he said if he had a gay son, he'd rather they were dead, but he won't have a gay son because he's educated. In 2002 said if he saw two men kissing in public he would "beat them". He said parents of children who are "a little gay" should whip them.
He's also called for women to be paid less than men because they get pregnant.
Mr Sandy says the South American nation is reeling from its worst recession and corruption scandal in recent history, and voters are very volatile.
"What you have now is a real polarisation between the far-right candidate that more and more people are supporting, and the traditional parties."
There are 13 candidates in all. If none of them get an outright majority, the top two candidates will go head-to-head in a second round of voting later this month.
Mr Bolsonaro is leading the polls, followed by far-left candidate Fernando Haddad.