From the 1980s until his candidacy for Federal Parliament, Cobb was active in, and spent three years as president of the New South Wales Farmers Association, a lobby group representing farmers and rural and regional communities.[4] He also continued to farm the family property.
In July 2005, Cobb was appointed to the ministry as Minister for Citizenship and Multicultural Affairs, but soon after was reshuffled to the community services portfolio.
After Parkes was dramatically altered in a redistribution, Cobb ran for the neighbouring seat of Calare at the 2007 election after the popular independent member Peter Andren retired. The Liberal-National Party Coalition lost the election, but Cobb won Calare handily. He was chosen by new Opposition leader Brendan Nelson to be a member of the shadow ministry, as the spokesperson on regional development and water security.[5] He was re-elected at the 2010 election and in September 2010 was appointed Shadow Minister for Agriculture and Food Security by Opposition leader, Tony Abbott.[6]
Cobb in married and has four daughters from his first marriage. He is not related to one of his predecessors as the member for Parkes, Michael Cobb.[2][8]