sentences:  On 10 December 1976 the Catholic People's Party together with the Anti-Revolutionary Party (ARP) and the Christian Historical Union (CHU) party choose to merge in a political alliance to form the Christian Democratic Appeal (CDA), the Chairman of the Christian Democratic Appeal Piet Steenkamp approached Van Agt to become the first Leader of the Christian Democratic Appeal, Van Agt accepted and became the Leader of the Christian Democratic Appeal and the first "lijsttrekker" (top candidate) of the Christian Democratic Appeal for the election of 1977.The Christian Democratic Appeal had 48 seats in the House of House of Representatives previously held by former parties and made a small win, gaining 1 seat and remained the second-largest party and now had 49 seats in the House of Representatives.Van Agt returned as a Member of the House of Representatives and became the parliamentary leader of the Christian Democratic Appeal in the House of Representatives, taking office on 8 June 1977 but he was still serving in the cabinet and because of dualism customs in the constitutional convention of Dutch politics he could not serve a dual mandate he subsequently resigned as Deputy Prime Minister and Minister of Justice on 8 September 1977.