Campaigning for Brazil presidential election begins

Lula may be in jail but his Workers' Party supporters have been out in force showing their support ahead of October's election

Campaigning for Brazil's wildly unpredictable presidential race officially got under way on Thursday with jailed former president Luiz Inacio Lula da Silva's name amongst the 13 candidates formally registered.

Candidates and their parties are now authorized to petition voters on the streets and online ahead of the October 7 poll.

Around a hundred participants from Lula's powerful leftist Workers' Party campaigned in front of Sao Paulo's Municipal Theater while Ciro Gomes of the center-left Democratic Workers' Party took to the streets of northern Rio de Janeiro promising to "save Brazil."

Environmentalist candidate Marina Silva, one of the front-runners, visited a health center in Sao Paulo while releasing an internet video calling on Brazilians to "make the change," after twice before falling short in presidential elections.

Former banker Henrique Meirelles of the center-right Democratic Movement party of unpopular outgoing President Michel Temer, promised on social media to deliver economic growth.

Former Sao Paulo governor Geraldo Alckmin of the center-right Social Democratic Party was due to take part in a women's meeting in his stronghold later in the day.

Campaigning, though, won't deflect from the major talking point in these elections, over whether or not the incarcerated Lula will be allowed to stand,

The 72-year-old is serving a 12-year sentence for accepting a seaside apartment as a bribe and under Brazil's clean slate law he is likely to be prevented from standing.

The electoral court has until September 17 to rule on Lula's candidacy and should he be barred, another former Sao Paulo governor, Fernando Haddad, would likely run in his place.

Lula still leads in the presidential polls ahead of right-winger Jair Bolsonaro, with Alckmin and Silva coming next.

Polls suggest voters are disillusioned with the state of their country as it struggles with recession and reels from a raft of corruption scandals.

Voting is obligatory in Brazil but some polls suggest at least a third of voters would skip it while another poll said a third were planning on deliberately spoiling their ballot.