Leader of Sinn Féin joined opposing sides with De Valera leading the Anti-Treaty faction, while Griffith joined the Pro-Treaty faction, which later became Cumann na nGaedheal. De Valera’ successor John J. O'Kelly was one of four leaders who served for brief periods of time as Sinn Féin’s party membership declined in favour of Fianna Fáil and Fine Gael. In 1937, Margaret Buckley became the first female President of Sinn Féin. During her thirteen years as leader, she vastly improved the relations between the IRA and the party. She was succeeded by Paddy McLogan and Tomás Ó Dubhghaill who both helped rebuild party support in
Fianna Fáil other members split from Sinn Féin when a motion he proposed—which called for elected members to be allowed to take their seats in Dáil Éireann if and when the controversial Oath of Allegiance was removed—failed to pass at the Sinn Féin Ard Fheis in 1926. The party adopted its name on 2 April of the same year. While Fianna Fáil was also opposed to the Treaty settlement, it rejected abstentionism, instead aiming to republicanise the Irish Free State from within. The party's platform of economic autarky had appeal among the farmers, working-class people and the poor while alienating more affluent