By Anthony Boadle and Jake Spring

BRASILIA (Reuters) - Brazilians began voting on Sunday in a polarized presidential race that could result in the election of a far-right former army captain, whose praise of past dictatorships enrages critics but whose promise of a brutal crackdown on crime and corruption has electrified his supporters.

Front-runner Jair Bolsonaro has surged in opinion polls in the past week, all but guaranteeing a spot in the second round of voting and raising a slim chance of a first-round victory.

He is riding a wave of anger at the establishment after the uncovering of one of the world's largest political graft schemes, opposition to a return to power by the leftist Workers Party (PT) blamed for much of that corruption, and fears about spiking crime in the country with more murders than any other.

But Brazil is split over what cost to its democracy it may pay if it chooses Bolsonaro, a long-time congressman who has repeatedly praised the 1964-85 military regime and suggested that opponents could only win through electoral fraud, although he now vows to respect the democratic process.

Geneis Correa, a 46-year-old business manager in Brasilia, said she voted for Bolsonaro and would support a coup if the PT wins, blaming the party for rampant corruption.

"If they win, it will become Venezuela, people will be hungry, with a currency that is worth nothing," she said, while exiting a polling station with her daughter.

"If the PT is voted into power and there is a military intervention, I would support it."

Bolsonaro's closest rival is PT candidate Fernando Haddad, a former mayor of Sao Paulo and one-time education minister. He is standing in for the party's imprisoned founder, former president Luiz Inacio Lula da Silva.

Many Brazilians like 65-year-old Ruth Pereira Santos fondly remember the years of rapid growth that Lula oversaw and benefited from his programs that lifted many out of poverty.

"Who could buy a car? Through the love of God today I have a car in my garage. This wasn't accessible before," said Santos, a caretaker for the elderly.

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Two polls published late on Saturday showed Bolsonaro had increased his lead over Haddad in the past two days, taking 36 percent of voter intentions compared with Haddad's 22 percent. The pair are deadlocked in a likely run-off vote on Oct. 28 that is required if no candidate takes a majority of valid votes on Sunday.

Polling stations opened at 8 a.m. (1100 GMT) and the last will close at 7 p.m. Brasilia time (2200 GMT). Exit polls and official results will start flowing in soon after that because Brazil uses an electronic voting system.

The 147 million voters will choose the president, all 513 members of the lower house of Congress, two-thirds of the 81-member Senate plus governors and lawmakers in all 27 states.

Almost two-thirds of the electorate are concentrated in the more populous south and southeast of Brazil where its biggest cities, Sao Paulo and Rio Janeiro, are located - and where Bolsonaro holds a commanding lead. A quarter of the voters are in the less developed northeast, traditionally a PT stronghold.





'WE HAVE EVERYTHING'

In the most polarized election since the end of military rule in 1985, Bolsonaro is backed by a group of retired generals who have criticized the PT governments from 2003-2016 and publicly advocate military intervention if corruption continues.

In a final appeal for votes on a live Facebook stream on Saturday night, Bolsonaro, 63, called on Brazilians to help him clean up the political system and establish better government of Brazil's rich mineral and agricultural resources.

"We have everything. What we need are politicians who are committed to their country and not to party interests," he said from his home, where he is recovering from a near-fatal stabbing at a campaign rally. He underwent two emergency surgeries and it is not clear how much campaigning he will be able to do if the vote heads into a runoff.

Bolsonaro, who has compared his campaign to that of U.S. President Donald Trump, dismissed as "fake news" accusations that he was sexist, racist and homophobic.

A Bolsonaro government would speed up the privatization of state companies to reduce Brazil's budget deficit and relax environmental controls for farming and mining. It would also block efforts to legalize abortion, drugs and gay marriage.

Haddad, who has presented himself as a fiscally responsible moderate, spent the last day of the campaign targeting undecided voters in the Bahia state in Brazil's northeast, the heartland of the PT's support, but where Bolsonaro has made gains in polling.

Haddad took Bolsonaro to task for skipping the last presidential debate on Thursday, which other candidates said was a sign he was unprepared to govern. Bolsonaro said he could not attend on the orders of his medical team.

The PT candidate said Bolsonaro wants to "win in the first round vote without having to debate the issues and that is bad for democracy."

"We have the ability to defeat what Bolsonaro stands for, in terms of reversing social gains, in terms of civility, in terms of solidarity and in terms of mutual respect," Haddad said.





(Reporting by Anthony Boadle and Jake Spring in Brasilia; Additional reporting by Eduardo Simões in São Paulo; Editing by Brad Brooks, Paul Tait and Nick Zieminski)