[5] At the 1921 election to Dáil Éireann, Maguire was returned unopposed as Teachta Dála (TD) for Mayo South–Roscommon South as a Sinn Féin candidate.

[6] 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%).

(Despite this ban, IRA officers Seán Farrell (Leitrim–Sligo) and John Madden (Mayo North) contested the election, the latter successfully).

In December 1938, Maguire was one of a group of seven people, who had been elected to the Second Dáil in 1921, who met with the IRA Army Council under Seán Russell.

According to J. Bowyer Bell, in The Secret Army, "With the possible exception of Tom Maguire, who went along, the Dáil members felt that the IRA request gave them the moral recognition so long denied by all factions and that their conditional devolution of power would in turn give the IRA the moral basis for the impending campaign" of 1939–45.

[fn 1] Maguire's support meant that the Provisional Army Council could claim to being the legitimate government of Ireland and the caretaker of true Irish Republicanism.

In The Irish Troubles, J. Bowyer Bell describes Maguire's opinion in 1986, "abstentionism was a basic tenet of republicanism, a moral issue of principle.

Abstentionism gave the movement legitimacy, the right to wage war, to speak for a Republic all but established in the hearts of the people.