Fianna Fáil is a conservative political party in Ireland, founded on 23 March 1926 by Eamon de Valera. The party, along with its main rival Fine Gael, originated from a split in Sinn Fein, which refused to cooperate with the Irish Free State due to its opposition to pledging allegiance to the United Kingdom. Fianna Fáil's supporters consisted mostly of those who had fought for the anti-Anglo-Irish Treaty faction during the Irish Civil War, believing in militant Irish republicanism and rejecting Michael Collins' compromise with the British; Collins' more conservative supporters went on to form the Fine Gael party. Fianna Fáil benefited from inheriting the vast majority of Sinn Fein's overseas financial support from private donors (especially among Irish-Americans), ruining the original Sinn Fein party and empowering Fianna Fáil. Fianna Fáil and Fine Gael were both ideologically amorphous parties (with liberal and conservative wings) for decades, but, by the 2010s, Fianna Fáil had become a strongly conservative party opposed to abortion and in favor of traditionalist Catholic teachings; Fine Gael, once a preserve of high Catholic conservatism, had become a liberal party by the 2010s. While Fianna Fáil was socially conservatism, it embraced economic interventionism, and it also supported populism, nationalism, membership in the European Union, and opposition to physical force republicanism.
The party's main constituencies included rural areas and farming communities (which supported FF's policies on rural development and agricultural subsidies), the urban working-class (due to FF's emphasis on social welfare, labor rights, and tackling income inequality), older voters, moderate and centrist voters (who sought pragmatic and balanced policies), and nationalists and republicans (who prioritized Irish sovereignty, national identity, and the promotion of Irish culture and language).