The latest polls put Lula, of the Workers' Party, the PT, 24 points ahead of his head-to-head rival Geraldo Alckmin of the Brazilian Social Democratic party, the PSDB. In the first round vote on October 1, the margin was just 6%.
"Lula had a great shock in not winning the first round against all the indications so he has intensified his campaign and put his face on the streets," Leonardo Barreto, professor at the institute of political sciences of the University of Brasilia, told Aljazeera.net.
"There is no one isolated fact why Lula has forged so far ahead in such a short time. Alckmin didn't manage to construct a brand which made him stand out. He couldn't criticise the social advances Lula has made, so he became ambiguous.
"He tried to use the issue of ethics but it wasn't enough, and to add to this he had internal struggles within his own party."
The Brazilian Advocates Organisation, OAB, has stated that it will consider a request for the impeachment of Lula in November if his Workers' Party, the PT, is re-elected.
Roberto Busato, the party's president, has compared Brazil to a pre-Nazi era.
"There has never been, in this country, a story of corruption so serious. The lack of confidence in the public institutions is what brought Hitler to power in Germany," he said.
Although no one is taking seriously the threat of impeachment, the story of corruption that has emerged in the home stretch of the elections and has left Brazil's 130 million voters joking about not knowing one from the other.
"We are such a rich country but we have all these thieves in power. It never ends. What can I do, pray?" says coconut-seller Ze Barbosa, a comment typical of the electorate.
Six people in Lula's inner circle - from his now-sacked campaign manager to his favoured barbeque-maker – have been accused of participating in the attempted sale of a dossier in an attempt to incriminate Alckmin, the former governor of Sao Paulo.
The question of where the $800,000 used in the attempted sting came from has hung in the air during the campaign in a clear suggestion that the funds came from illegal means, possibly from organised crime.
"I have disputed many presidential elections [five] and even when I've been behind, I have never played dirty. Why would I do that when the polls say I will win?" said Lula.
All this follows the worst corruption scandal in more than a decade, with the PT accused of having been paid $12,500 in monthly bribes to deputies in allied parties in exchange for support for passing bills.
Money allegedly used to buy
documents to influence voting
That episode cast a long shadow over the future of the party's president, treasury minister, chief of staff and secretary-general among many others.
When he became the first working-class president in Brazil four years ago, Lula's slogan was "hope against fear". One satirist has suggested that this time it is a battle between disillusion and disillusion.
University of Brasilia's Barreto said: "In 2002 we voted for the best option. In 2006 we are voting for the least worst. There is widespread discontent with the political class because of a series of scandals over the past four years, and not just in Lula's party."
No alternate saviour
Among the Brazilian electorate is a sense of scorched earth, that there is not alternate saviour and that rival candidates are very much two faces of the same coin.
However, Lula seems to have an edge based on his social programmes which resonate with the poor and disenfranchised. These could be the deciding factor in the second round.
"There's still a doubt about the long-term sustainability of this. He still needs to find a way to consolidate the costs of these social programmes with the administration of tax," Barreto said.
For Latin America as a whole, that has seen a succession of left-wing presidents coming to power since Lula's first victory, a second mandate is the final nail in the coffin of the discredited Washington Consensus.
Lula's position of continental torch-bearer has been eroded by the enigmatic Venezuelan premier Hugo Chavez, who himself goes to the polls in December.
"In Latin America this is a new chance for Lula to consolidate himself as leader and to lead Brazil as a global player. The position of Brazil as a leader in the continent is questioned by many neighbouring countries and he can start a new cycle of negotiations," said Barreto.
Final voting in Brazil's Presidential election, which is compulsory, takes place on October 29. Results will be almost instantaneous with the world's biggest electronic voting system.