Democratic Left Alliance-Labour Union (Polish: Sojusz Lewicy Demokratycznej-Unia Pracy, SLD-UP) was an electoral committee and a coalition of two Polish centre-left political parties: Democratic Left Alliance and Labour Union.

The SLD-UP won a stunning victory at the 2001 parliamentary elections, gaining 41% of the vote, and formed the government with the Polish People's Party.

During the 2001–2005 term, there occurred a splintering of the alliance and there came into being four left-wing political caucuses in the Polish parliament: The SLD-UP maintained their alliance for the European parliamentary elections of 2004, and won five seats with 9.3% of the vote, a sharp decline from the national elections in 2001.

In the 2005 parliamentary elections, SDPL, Labour Union and Greens 2004 formed a joint electoral committee, under the leadership of the SDPL, and most of the PLD members joined Self-Defense of the Republic of Poland.

Following the relatively poor performance of the SDPL-UP-Greens at the 2005 parliamentary elections (they polled 3.9% and failed to break the 5% parliamentary threshold), and the overwhelming success of right-wing parties, the SDPL and UP sought to reapproach the SLD, and seek a new understanding.