Socialism and Liberty Party

PSOL also allows certain unregistered political parties to launch candidates through its TSE registry number. These organizations, however, cannot participate in the party's congresses.

Clécio Luís, Mayor of Macapá, left the party to join Sustainability Network.

PSOL launched Heloísa Helena to run for president in 2006 elections. The vice-presidential candidate was intellectual César Benjamin. The party ran in a left-wing ticket along with two other parties: Trotskyist Unified Workers' Socialist Party (PSTU) and Marxist–Leninist Brazilian Communist Party (PCB).

The alliance was extended to gubernatorial elections. In Minas Gerais, for instance, Vanessa Portugal, from the PSTU, ran for governor with PSOL's support, although not with PCB's. Prominent PSOL gubernatorial candidates were Plínio de Arruda Sampaio in São Paulo, Milton Temer in Rio de Janeiro and Roberto Robaina in Rio Grande do Sul. However, they were all defeated.

Heloísa Helena finished the presidential race in the third place, receiving 6.5 million votes throughout the country (6.85% of the valid votes). Three federal deputies, Luciana Genro, Chico Alencar and Ivan Valente, managed to get re-elected.

In the 2010 candidate for presidential election Plínio de Arruda Sampaio received 888.000 votes (0.87%). Plinio presented an agrarian reform project in 1964 when he was federal deputy, but the 1964 Military Coup ended the project and Plinio lost his mandate. Although he received very few votes Plinio became famous after the elections because he was qualified as an anti-candidate.

PSOL elected three deputies again, Chico Alencar, Ivan Valente and Jean Wyllys.

Toninho do PSOL from Federal District got the best gubernatorial result. He finished in third place with 14.25%.

In 2012 PSOL got its best results so far. Clecio Luis and Gelsimar Gonzaga were elected mayors in Macapá, Amapá's state capital, and Itaocara.

In the northern second largest city Belém and in Rio de Janeiro, PSOL finished second and elected four city councillors – the second largest group in those councils. In Belem Edmilson Rodrigues got 43.39% and in Rio de Janeiro Marcelo Freixo got 28.15%, almost 1 million votes.

Other places like São Paulo, Fortaleza, Campinas, Belo Horizonte, Curitiba, Salvador, Natal, Florianópolis, Niterói, São Gonçalo and Pelotas, PSOL got respectable results in 2012, 49 city councillors from PSOL were elected.

PSOL initially nominated Randolfe Rodrigues, the Senator for Amapá, as their candidate for President in 2014, with former federal deputy and party co-founder Luciana Genro as his running mate.[13] Federal deputy Chico Alencar of Rio de Janeiro and attorney Renato Roseno also ran for the party's nomination. However, he was replaced at the top of the ticket by Genro, a member of the Left Socialist Movement faction. She got 1,612,186 votes finishing in 4th place.

Genro's campaign received the support of important Brazilian intellectuals and celebrities. These included like Chico de Oliveira, Rogério Arantes, Vladimir Safatle, Michel Löwy, Gregorio Duvivier, Valesca Popozuda, Zélia Duncan, Karina Buhr, Clara Averbuck, Marina Lima, Juca Kfouri, Preta Gil, Laerte Coutinho, Marcelo Yuka and the international popstar Jessica Sutta. Her candidacy was well-regarded in the LGBT community.

PSOL elected 5 federal deputies and 12 state deputies. Marcelo Freixo (RJ) received the highest vote for a state deputy in Brazil with 350,408 votes. Carlos Giannazi was the leftist most voted in São Paulo with 164,929 votes.

Gubernatorial candidates Tarcísio Motta (RJ) with 8.92% (14.62% in city of Rio Janeiro) and Robério Paulino (RN) with 8.74% (22.45% in capital Natal) got excellent results. Senate candidate Heloísa Helena (AL) got 31.86%, but she lost the election to former Brazilian president Fernando Collor de Mello, who was impeached.

In 2018, PSOL chose prolific labor leader Guilherme Boulos as their nominee for the presidency. Boulos's close affiliation with former President Lula led to concern that his nomination would erode PSOL's distinct identity.[14] It was alleged that party leadership pushed Boulos at the expense of other pre-candidates for the party's nomination, including economist (and son of 2010 presidential nominee Plínio de Arruda Sampaio) Plínio de Arruda Sampaio Jr., activist and educator Hamilton Assis, and academic Nildo Ouriques. Indigenous leader Sônia Guajajara, who initially sought the party's nomination, was chosen to serve as his vice presidential running mate.

On 30 April, PSOL made official its support for the pre-candidacy of Luiz Inácio Lula da Silva (PT) for the presidency. The party approved its support during electoral conference.[15] On the 7 May, PT made official the pre-candidacy of ex-president Lula and ex-governor of São Paulo Geraldo Alckmin (PSB) to run for president.[16] In June, a group of PSOL affiliates created a dissident movement of the party in protest against the support to the pre-candidacy of former president Luiz Inácio Lula da Silva (PT) and former governor Geraldo Alckmin (PSB) for the presidency.[17]