 In January 1919, Sinn Féin MPs refused to recognise the Parliament of the United Kingdom and instead assembled at the Mansion House in Dublin as a revolutionary parliament called Dáil Éireann, though Sears did not attend as he was in prison.He was elected unopposed as a Sinn Féin Teachta Dála (TD) for the Mayo South–Roscommon South constituency at the 1921 elections.He supported the Anglo-Irish Treaty and voted for it.