A sometimes polarizing figure on his party's right, Koch proved to be one of the main defenders of business and financial interests within his party. In 2010, Koch and Merkel clashed over budget cuts, as Koch proposed cutbacks in education and research that Merkel opposed. He also suggested that a law passed to provide a guaranteed child-care facilities for children under 3 would have to be reconsidered. In his final years as Minister-President, he largely worked smoothly with Merkel. Ahead of the Christian Democrats’ leadership election in 2018, Koch publicly endorsed Friedrich Merz to succeed Angela Merkel as the party's chair.