Mark it down as a poor night for Brazilian democracy and tolerance. The penultimate televised debate before next weekend’s presidential election was overshadowed by the homophobic rant of one of the fringe candidates.

Levy Fidelix is a conservative and former journalist who has no hope of winning, with a support rate below 1%. But given almost equal airtime to the leading candidates on national television on Sunday, he let rip with a torrent of invective.

The presidential hopeful claimed homosexuals “need psychological care” and were better kept “well away from [the rest of] us”.

He joked that Brazil’s population of 200 million would be reduced by half if homosexuality were encouraged because “the excretory system” does not function as a means of reproduction.

His comments went unremarked upon by the three main candidates – incumbent Dilma Rousseff of the Workers party, former environment minister Marina Silva and Aécio Neves of the pro-business Social Democratic party – though his insults quickly dominated post-debate discussion on social networks.

The incident highlighted the challenge of maintaining fairness in a campaign with 12 candidates, only seven of whom are entitled to take part in the televised debates because their parties are in Congress, with all seven getting near-equal prominence in the debates despite four of them usually polling less than 1%.

The convoluted format for Sunday night’s one-hour encounter had several different sections, including one in which the candidates were obliged to ask a rival a question. Several times, the would-be leaders appeared unsure of the rules and either under- or overran their time, leaving their voices fading off. If that was not enough to ensure a low audience, the debate was broadcast live at midnight, when most people were asleep.

Nevertheless, the campaign has been largely compelling and remains too close to call. According to the most recent polls, Rousseff will win the first round on 5 October and then face a run-off with Silva on 26 October. Second-round vote intentions have swung back and forth between the two, though the president recently opened up a narrow lead.

With less than a week until polling day, the televised debate should have been an opportunity for the leading candidates to provide details about their programmes of government and to highlight weaknesses in their rivals’ positions. Instead it was mostly a mix of bland statements and character attacks.

Rousseff accused Silva of falsely claiming that she supported the tax on financial transactions, even though she voted against it four times. Political adverts during the commercial break tried to reinforce this message of “Marina the liar”. The president said she was the most reliable and experienced of the candidates. “I humbly beg your vote,” Rousseff said.

Silva, who has about 80% less airtime and advertising money than the incumbent, presented herself as the face of change for a united Brazil that was in thrall neither to a “monopoly of the left or the right”. She criticised Rousseff for dodging questions, failing to address runaway crime rates and neglecting the ethanol industry and options for a cleaner, more diverse energy mix.

Looking forward to the runoff, she ended by saying: “In the second round, we will have more time, equal time and other opportunities to show our programme.”

Neves attacked Rousseff over a corruption scandal at the nation’s biggest company, Petrobras. But his performance was unlikely to lift him beyond third place.

With these three candidates vying for the middle ground with vanilla statements, the four fringe candidates stole the show with punchier lines and more radical viewpoints. Luciana Genro from the Socialism and Liberty party, made impressive use of her time to highlight the flaws in rival programmes and to warn of the social dangers of homophobia. As in previous debates, the Green party’s Eduardo Jorge also won plaudits for his grasp of detail and support for marijuana liberalisation.

That left televangelist pastor Everaldo Pereira, who is running on an anti-abortion, anti-gay rights platform, came across as relatively moderate in comparison with Fidelix.

The final debate takes place on Thursday.

• This article was amended on 30 September 2014 to clarify that there are a total of 12 candidates in the presidential election.

