Fine Gael stood aside hoping to inflict damage on Fianna Fáil, which won, though Donnellan secured almost 30% of the votes cast.

At the first Ard-Chomhairle of Clann na Talmhan in March 1943, he stated that the party's reason for existing was to "break the stranglehold of the money-grubbers and Jews".

Donnellan, however, proved too radical for the party members from the province of Leinster, due to his more left-wing leanings: He supported land redistribution in cases where large farmer holders were being inefficient as well as free access to education and healthcare.

Donnellan's decision to abstain on Éamon de Valera's nomination for Taoiseach in 1943 led some to suspect he had done so out of loyalty to his old party leader.

In his youth Donnellan was a talented footballer who won an All-Ireland SFC medal with the Galway county team in 1925, captaining them in their 1933 defeat to Cavan.