He lost the election to Sinn Féin's Sean McEntee (then in prison and later Finance Minister in the first De Valera led Government in the Irish Republic).

In 1934, he was elected to the Parliament of Northern Ireland in a by-election as Stormont MP for Belfast Central, resigning his seat in the Senate.

Campbell has been described as having a "Redmondite approach and rigid attachment to attendance and parliamentary etiquette (which) ruled him out as a unifying influence" on his own party after the death of its leader Devlin.

In November 1945, he resigned his Belfast Central seat and retired from politics in order to take up a position as a County Court Judge.

He married Norah Gilfedder on 11 February 1918 in St Patrick's Church, Belfast and had five children, one daughter and four sons one of whom – Joseph – became a priest of the Diocese of Down and Connor.