Self-Defence of the Republic of Poland is a nationalist, socialist, populist, and agrarian political party and trade union in Poland. The party promotes agrarian socialist and Catholic socialist economic policies combined with a left-wing populist, anti-globalization and anti-neoliberal rhetoric. The party describes itself as left-wing, although it stresses that it belongs to the "patriotic left" and follows Catholic social teaching. The party is sympathetic to Communist Poland, which led political scientists to label the party as neocommunist, post-communist, and far-left.

The Democratic Left Alliance was a social-democratic political party in Poland. It was formed on 9 July 1991 as an electoral alliance of centre-left parties, and became a single party on 15 April 1999. It was the major coalition party in Poland between 1993 and 1997, and between 2001 and 2005, with four Prime ministers coming from the party: Józef Oleksy, Włodzimierz Cimoszewicz, Leszek Miller and Marek Belka. It then faded into opposition, overshadowed by the rise of Civic Platform and Law and Justice.