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Seán Lemass, a prominent figure in Irish politics, was a member of Fianna Fáil, a political party in Ireland. Founded in 1926, Fianna Fáil espouses republican and centre-right policies. Lemass played a pivotal role in shaping the party's policies, serving as its leader and overseeing economic development and social progress during his tenure as Taoiseach (prime minister) from 1959 to 1966.