Campbell was born in Belfast, Northern Ireland, and worked as a shipwright, including at the Williamstown dockyard, before entering politics.
He was a member of the executive of the Australian Council of Trade Unions between 1987 and 1997 and ACTU Senior Vice-president from 1993 to 1997.
He was a prominent member of the Socialist Left faction of the ALP, and a leading critic of the U.S.-Australia Free Trade Agreement.
Campbell was Parliamentary Secretary to the Shadow Minister for Industry, Innovation, Science and Research 2001–04.
In April 2007, facing near-certain defeat in a preselection challenge by former protégé Doug Cameron, he announced that he would retire at the end of his term in the Senate.