P.T. Thomas forayed into the political landscape of the state when he was a school-going student. During his school days, he started to ideologically like and follow the Indian National Congress. Moreover, he started getting helps and mentorships from the senior members of the students’ wing of the Congress party. As the years progressed, he rose to the high-rungs of the students’ wing. For instance, he became the Vice President of Kerala Students Union unit at Mar Ivanios College when he was doing his pre-degree course over there. Later, he became the General Secretary of the College Union as well. Climbing the hierarchical ladder in the students’ wing of the party, he was later elected as the President of Idukki unit of Kerala Students Union. He still climbed the hierarchical ladder in the party and became the State General Secretary and the State President at different points in time. Finally, he rose to become the member of the State unit of the party.

In the state unit of the party, P.T. Thomas showed his capability as a leader and gathered the people on various issues concerning the state. Hence, he was made the executive committee member of the Kerala Pradesh Congress Committee. This committee identified the causes and effects of various issues plaguing the state unit of the Congress party. His good work was recognized by the national leaders of the party and elevated him to the All India Congress Committee as its executive member at one point in time. Subsequently looking at the popularity in his place of activity, he was given a ticket to contest the state general elections, and on two occasions, he was successful in becoming the Member of Kerala Legislative Assembly. In the year 2009, he was elected to the 15th Lokh Sabha. He reached the parliament to represent the people of the Idukki Lokh Sabha Constituency.