Modern British political arena is witnessing a radical reform in the Conservative party, ever since David Cameron’s leadership election in 2005. Compassionate Conservatism is promoted as the essential reforming ideology for attracting electorate support to regain the government. Through progressive approaches of limiting the government and empowering individuals and society, David Cameron has made great progress in rebuilding the party to be a center-right party representative of the wide British public. This paper studies the construction of the new Conservative party ideology, Compassionate Conservatism, from political linguistic angle. Prime Minister’s Question Time (PMQ) is chosen as the crucial channel for detailed analysis using critical discourse analysis approaches. This paper firstly examines PMQ as a highly institutionalized genre where the verbal exchange between the PM and the Opposition leader is constrained. Secondly, the view of dynamic power relations is maintained in analyzing the macro and micro discourse features of David Cameron’s questioning performance in combating Tony Blair in the adversarial PMQ discourse. Thirdly, the analysis further demonstrates that beyond the practice of debate and dispute, Cameron’s questioning discourse also has the effect of projecting the reforming party ideology of Compassionate Conservatism. It is concluded that both textual features and pragmatic functions of Cameron’s questioning discourse has the essential role in combating Blair’s challenges and constructing the desired image for the Conservative party and leadership. This study necessitates future studies of political linguistics to investigate British party politics through the crucial genre of PMQ.