After months of negotiations and two special delegate conferences, Democratic Left merges with the Labour Party on January 24, 1999.

Democratic Left is formed after a split in the Workers’ Party of Ireland, which in turn has its origins in the 1970 split in Sinn Féin and, after seven years in existence, it is incorporated into the Labour Party in 1999. Although never formally styled as a communist party, the Workers’ Party has an internal organisation based on democratic centralism, strong links with the Soviet Union, and campaigns for socialist policies. However between 1989 and 1992 the Workers’ Party is beset by a number of problems.

On February 15, 1992, a special conference is held in Dún Laoghaire to reconstitute the party. A motion proposed by Proinsias De Rossa and general secretary Des Geraghty seek to stand down the existing membership, elect an 11-member provisional executive council and make several other significant changes in party structures but it is defeated by nine votes.

After the conference it is clear a split is inevitable. At an Ard Chomhairle meeting held on February 22, 1992 in Wynn’s Hotel in Dublin, six of the party’s TDs resign from the party along with more than half of the Ard Chomhairle. The new breakaway party is provisionally named New Agenda with De Rossa becoming leader of the party.

In the 1997 Irish general election Democratic Left loses two of its six seats, both of its by-election victors, Eric Byrne in Dublin South-Central and Kathleen Lynch in Cork North-Central, being unseated. The party wins 2.5% of the vote. The party also is in significant financial debt because of a lack of access to public funds, due to its size. Between 1998 and 1999 the party enters discussions with the Labour Party which culminates in the parties’ merger in 1999, keeping the name of the larger partner but excluding members in Northern Ireland from organising. This leaves Gerry Cullen, their councillor in Dungannon Borough Council, in a state of limbo, representing a party for whom he can no longer seek election.

The launch of the merged party is in the Pillar Room of the Rotunda Hospital in Dublin on January 24, 1999. Labour Party leader Ruairi Quinn remains leader of the unified party, while De Rossa takes up the largely titular position of party president. Only 10% of Democratic Left delegates at the special conference had voted against the merger. De Rossa successfully contests the 1999 European Parliament election in Dublin. He holds his Dáil seat until he stands down at the 2002 Irish general election. He holds his European Parliament seat in the 2004 election and 2009 election.

In 2002, former Democratic Left TDs Pat Rabbitte and Liz McManus are elected as Labour Party leader and deputy leader respectively. When Rabbite steps down as Labour leader after the 2007 Irish general election, Eamon Gilmore is elected unopposed as his successor.

The party archives are donated to the National Library of Ireland by the Labour Party in 2014. The records can be accessed by means of the call number: MS 49,807.