His political career began in 1978, when he became involved in the Human Rights and Legal Aid Programme with the leader of the New Jewel Movement, Maurice Bishop.

In December 1984, Thomas was elected to the House of Representatives from St. Patrick East constituency, and from 1984 to 1990, he was a Junior Minister in the Ministry of Legal Affairs.

[5] After spending 13 years in opposition,[2] the NDC won the general election held on 8 July 2008, taking 11 out of 15 seats and defeating the NNP.

[7][8] On 9 July Thomas was sworn in as Prime Minister[2][6][8] at the Grenada Trade Centre in Grand Anse, St. George's by Governor-General Daniel Williams.

Two members of non-governmental organizations who were not affiliated with the NDC were included in the cabinet: Franka Bernadine as Minister of Education and Human Resources, and Jimmy Bristol as Attorney-General.