Then there are the ads for candidates expressing acute indignation with the status quo, like those of Tiririca, 49, a clown whose stage name translates as “Grumpy.” (His real name is Francisco Everardo Oliveira Silva.) His television spots this year have him performing a cringe-inducing imitation of Roberto Carlos, the 73-year-old titan of Brazilian pop music. He is running against the system, even though he is an incumbent: São Paulo voters elected him to a seat in Congress in a landslide in 2010.

“There’s a rich history of Brazilian voters’ expressing disgust at the ballot box,” said David Fleischer, professor emeritus of political science at the University of Brasília. As long ago as 1959, he said, Cacareco, a rhinoceros at a Brazilian zoo, received more than 90,000 votes as a write-in candidate for the São Paulo City Council, outpolling all the human candidates in the race.

A more recent pioneer was Enéas Ferreira Carneiro, a neofascist cardiologist with a long, dark, ZZ Top-style beard who founded the Party for the Rebuilding of the National Order and won a seat in Congress in 2002 with 1.5 million votes. His rabid television ads ended with the same growling phrase: “My name is Enéas.”

Mr. Carneiro died in 2007 at the age of 68, but other candidates continue to riff on his style, including Havanir Nimtz, 60, a São Paulo dermatologist who is running for Congress this year. She delivers her message in a rapid-fire rant and ends by shouting her name at viewers.

Candidates of all stripes are generally able to broadcast such ads in Brazil because of legislation requiring television stations to provide free airtime to candidates during a campaign. With a month to go before the election on Oct. 5, prime-time viewing here can be a surreal experience. Sometimes the wacky ads carry a candidate to victory, as they have for Tiririca the clown. But much of the time they don’t seem to help, even in a country where voting is mandatory and the political spectrum is fragmented among more than 20 parties represented in Congress.