His working in the United States includes teaching at Oberlin College, Ohio, and practising law with the Legal Aid Society of Cleveland and the Cleveland, Ohio, Law Office of Forbes, Forbes and Teamor. He returned to Ghana, where he became a school administrator.
Deputy Foreign Secretary
Chambas first entered government in 1987 as Deputy Foreign Secretary of Ghana. He was a member of the Head of State's summit delegations to a number of countries, including the US, China, UK, France, Malaysia, Nigeria, and Zimbabwe. He led Ghana's delegation to the UN General Assembly, ministerial meetings of the OAU and the Economic Community of West African States, the Non-Aligned Movement, and the Commonwealth.
MP 1993–1996
He served as MP for Bimbilla from 1993 to 1996 on the ticket of the National Democratic Congress. He was First Deputy Speaker of the Ghanaian Parliament, and thereafter was appointed Deputy Foreign Minister. As First Deputy Speaker, he was Chairman of the Appointments and Privileges Committees of Parliament. In 1993–94, he chaired the Foreign Affairs Committee of Parliament with oversight responsibility for the Ministry of Foreign Affairs.
Civil War mediator
Chambas came to international importance as mediator between the parties of the First Liberian Civil War of the 1990s, and later the Ivorian Civil War in the early 2000s. Centrally involved in the ECOWAS mediation efforts in Liberia, he directly participated in negotiations leading to the agreements ending the Liberian civil war. In the interim, Chambas lost his Parliamentary seat in 1996, and the then government of President Jerry Rawlings removed him from the foreign ministry and put him in charge of Ghana's primary education system.
Between April 1997 and December 2000, Chambas was appointed the Deputy Minister of Education in charge of tertiary education. In that capacity, he had direct responsibility for the country's five universities, 10 polytechnics and agencies/institutions charged with formulation of policies on higher education, accreditation and maintenance of standards in tertiary institutions. Dr Chambas was involved in reform of tertiary education which included diversification of funding, cost sharing, the introduction of the Ghana Education Trust Fund, aimed to improve the quality and financial standing of tertiary institutions. He also led negotiations and conflict resolution processes during student protests and industrial disputes involving university and polytechnic teachers and other staff members. Chambas was at the time suggested in the Ghanaian press as a candidate for the New Patriotic Party.
Return to parliament
Regaining his seat in 2000, he was also a member of the Commonwealth Ministerial Action Group, which worked to facilitate a transition to constitutional democratic governance in Nigeria, Sierra Leone and the Gambia. Reelected on 7 December 2000 on the ticket of the National Democratic Congress. Shortly thereafter, he was nominated to head ECOWAS by Ghanaian President John Kufuor. In 2002, he was the Ranking Member on the Parliamentary Select Committee on Foreign Affairs of the Minority National Democratic Congress. He was also a member of the Select Committee on Education and the Committee on Subsidiary legislation.