Passage: Strauß took the discord as a starting point to evaluate chances of expanding the CSU on the federal level, such as having separate electoral lists in the states of North Rhine-Westphalia, Lower Saxony, Hamburg, and Bremen. He hoped to draw away right-wing voters from the FDP towards the CSU and went as far as having private meetings with industrialists in North Rhine-Westphalia. These attempts led to discomfort within the membership base of the CDU and hampered both parties' chances in the upcoming elections. Kohl himself remained silent during these tensions, which some interpreted as a lack of leadership, while others such as future president Karl Carstens praised him for seeking a consensus at the centre of the party. In the 1976 federal election, the CDU/CSU coalition performed very well, winning 48.6% of the vote. They were kept out of government by the center-left cabinet formed by the Social Democratic Party of Germany and Free Democratic Party, led by Social Democrat Helmut Schmidt. Kohl then retired as minister-president of Rhineland-Palatinate to become the leader of the CDU/CSU in the Bundestag. He was succeeded by Bernhard Vogel.

Question: Prior to leading the CDU/CSU what did Kohl do?
minister-president of Rhineland-Palatinate