Social Democracy of Poland

The party was founded in April 2004 as a splinter group from the post-communist Democratic Left Alliance (SLD). The SDPL should not be confused with a former party the Social Democracy of the Republic of Poland (SdRP) which existed between 1990–99 and was a direct predecessor of the SLD.

SDPL contested its first elections in June 2004, this being for Polish representation to the European parliament. The party gained 5.3%, which saw three members elected to parliament. In May 2005 the party reached an agreement with Labour Union (UP) and Greens 2004 to jointly contest for the forthcoming Polish parliamentary elections, under the SDPL banner. SDPL managed to gain 3.9% of the vote, but fell short of the 5% threshold required to win parliamentary representation. SDPL put forward its party leader Marek Borowski, as candidate for the Polish presidential elections held in the following month of October. Borowski came fourth in the first round, winning 10.3% of the vote.

On 3 September 2006, SDPL joined the newly formed Left and Democrats (LiD) coalition, made up of the centre-left parties SDPL, SLD, UP and the centrist Democratic Party – demokraci.pl. This alliance was created with a view to jointly contest the upcoming local government elections. The LiD alliance was maintained for the Polish parliamentary elections of October 2007, and LiD achieved 13.2% of the vote. This translated into 53 lower house seats, 10 of which were won by SDPL.

After LiD dissolved, 8 out of 10 SDPL MPs formed a new parliamentary caucus called Social Democracy of Poland – New Left (Socjaldemoracja Polska – Nowa Lewica, SDPL-NL).

On 3 February 2013, SDPL leader Wojciech Filemonowicz and Palikot's Movement leader Janusz Palikot stated an ambition to form an electoral alliance between the two parties to contest the European elections in 2014.^[3][4] The alliance was named Europa Plus. The SDPL withdrew from the alliance, along with the Union of the Left, on 7 February 2014.^[5]