[5][6][7][1][8] In 1922 he was expelled from the Labor Party along with Edmund Dwyer-Gray for disloyalty; Mahoney was alleged to have associated with people who had opposed endorsed Labor candidates, and who had endorsed direct action and "go slow" tactics and supported the Industrial Workers of the World in his presence.

[19][20][6][21] He also contested the 1928 state election as an Independent Labor candidate in light of the continual refusal of his requests for readmission and polled well, but was again defeated.

[30] He immediately announced that he would stand "four-square behind" leader James Scullin in a party still dealing with the aftermath of the 1931 Labor split.

[35] He sought preselection to recontest his old seat at the 1943 federal election, but the state executive refused to endorse his candidacy.

[39] Mahoney sought readmittance to the Labor Party in March 1944 following his automatic removal for opposing an endorsed candidate, but was instead formally expelled.

[42] In 1950, Mahoney supported the proposed banning of the Communist Party of Australia at the Labor Party conference, declaring that Robert Menzies "should 'do the job'" and described communism as a "bogey brought about by the Menzies Government to crucify the trade union movement".