A deeply polarized Brazil stood at a political crossroads yesterday as the bruising first round of the presidential election left voters with a stark choice in the run-off between far-right firebrand Jair Bolsonaro and leftist Fernando Haddad.

Bolsonaro, an ultraconservative former paratrooper, easily beat a dozen other candidates on Sunday -- but not by enough to avoid an October 28 showdown with Haddad, the former mayor of Sao Paulo.

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Bolsonaro won 46 percent of the vote to Haddad's 29 percent, according to official results.

That tracked closely with pollster's predictions, but Bolsonaro charged that "polling problems" had cheated him of outright victory in the first round, which required him to pass the 50 percent threshold.

Some of his supporters protested outside the national electoral tribunal in the capital Brasilia, chanting "Fraud!"

Fernando Haddad (R), presidential candidate of Brazil’s leftist Worker Party (PT), reacts with supporters, in Sao Paulo, Brazil October 7, 2018. Photo: Reuters

That anger reflected the uncertain outlook for the second round.

Surveys suggest Bolsonaro will have the edge, but that Haddad will draw nearly even with him after picking up substantial support from the defeated candidates.

"We expected to win in the first round," one Bolsonaro voter, 77-year-old retiree Lourdes Azevedo, said bitterly in Rio de Janeiro.

"Now things are more difficult: the second round is a risk."

Haddad, addressing his own supporters, called the looming run-off "a golden opportunity," and challenged Bolsonaro to a debate.

He replaced popular former president Luiz Inacio Lula da Silva in the race after Lula, imprisoned for corruption, was disqualified.

Despite his complaints, Bolsonaro did not formally contest Sunday's result, saying his voters "remain mobilized" for the second round.