Sinn Féin for nine years. (It merged with two other organisations to form Fine Gael in 1933.) Anti-Treaty Sinn Féin members continued to boycott the Dáil. At a special "Ard Fheis" in March 1926, de Valera proposed that elected members be allowed to take their seats in the Dáil if and when the controversial Oath of Allegiance was removed. When his motion was defeated, de Valera resigned from Sinn Féin; on 16 May 1926, he founded his own party, Fianna Fáil, which was dedicated to republicanising the Free State from within its political structures. He took most Sinn Féin TDs with him.
Fianna Fáil and Sinn Féin. The party dominated Irish political life for most of the 20th century, and since its foundation either it or Fine Gael has led every government. Between 1989 and 2011, it led coalition governments with parties of both the left and the right. Fianna Fáil was last in government from 1997 to 2011 under Bertie Ahern and Brian Cowen, with a periodic high of 81 seats in 2002, reduced to 77 in 2007 and then to 20 in 2011, the lowest in the party's history. Having won 44 seats at the 2016 general election, Fianna Fáil is currently