RIO DE JANEIRO, Sept. 18 (Xinhua) -- Less than three weeks to go before Brazilians go to the polls to elect a new president on Oct. 7, the election is revealing an increasingly polarized society, according to political observers.

Pre-election surveys and the candidates' social media campaigns are painting a picture of a country divided into two distant camps: the progressives on the left and the ultra-conservatives on the right.

What is becoming apparent is an increasingly polarized scenario between the radical far right represented by candidate Jair Bolsonaro and the old left represented by the Workers' Party (PT), said Carlos Pereira, a political scientist at the Getulio Vargas Foundation, a think tank and center for higher studies.

The far-right Social Liberal Party candidate Bolsonaro's leading rival is former Sao Paulo mayor Fernando Haddad, who became the PT's presidential candidate after ex-president Luiz Inacio Lula da Silva was declared ineligible.

The latest poll, released on Monday, showed Bolsonaro is still in the lead with 28.2 percent of support among voters and Haddad with 17.6 percent.

Haddad was officially announced as Lula's replacement last week, so his rapid rise to second place shows his candidacy is enjoying popular support.

Former state governor Ciro Gomes, candidate of the leftist Democratic Labor Party, is in third place with 10.8 percent support. Another 10 candidates are in the running.

"This polarization was started by the right in recent years with the PT governments of Lula and then Dilma Rousseff," Pereira said.

Both were reelected, though Rousseff was unable to conclude her second term after being impeached by a conservative-controlled congress.

The polarization "is most obvious on social networks," said the academic, adding that as the election day draws near, "the attacks between the candidates ... will become more evident and they will reveal the polarization."

A likely runoff on Oct. 28 between Bolsonaro and either Haddad or Gomes will split the country even more, he predicted.

"I think everything will be much more polarized in the runoff. I imagine both sides will resort to fear tactics in their campaigns, showing what a presidency under Bolsonaro would be like on the one hand, and what could happen if the PT returns to power on the other," Pereira said.

"There are still three weeks to go and a lot can change, but the scenario seems to be a done deal, at least in the first round," he added.

"The great unknown" lies in the "gripping" Oct. 28 runoff, said Pereira, since Brazil's political parties will then form alliances behind the top two candidates to either "impede a Bolsonaro victory or a win by the PT. It's impossible to make any predictions for Oct. 28."

Marco Aurelio Nogueira, a political scientist at the University of Sao Paulo, believed the country's more polarized landscape first came to light in 2014.

"The polarization was already evident in the last elections, when Dilma Rousseff defeated Aecio Neves of the right, but by a very narrow margin," said Nogueira.

"What had until then been political polarization spreads to form part of the day-to-day life of the people, not just the politicians," he said.

The division among Brazilians can best be seen on the Internet, which is teeming with negative campaign ads against the two front-runners Bolsonaro and Haddad.

"Without a doubt, the social networks will play a more decisive role in the runoff," said Nogueira, who also expects a finale between Bolsonaro and either Haddad or Gomes.