 He opposed the Anglo-Irish Treaty, and apart from saying "Níl" ("No" in English) when the vote was called, did not participate in any substantial way in the Dáil treaty debates.He was returned unopposed at the 1922 general election.At the 1923 general election, Maguire faced a contest and succeeded in securing the second of five seats in the Mayo South constituency, winning 5,712 votes (17.8%).