After serving as a delegate and a clerk for the 1868 state convention that drafted a new state constitution, O'Hara—a Republican—served in the North Carolina House of Representatives from 1868 to 1869. In 1873, he was elected chairman of the Halifax County board of commissioners.
After participating in the drafting of a new state constitution for North Carolina as a delegate and clerk in 1868, O'Hara—a Republican—held positions in the North Carolina House of Representatives from 1868 to 1869. In 1873, he was elected chairman of the Halifax County board of commissioners.