On a scholarship of Robert Bosch Foundation, Lange taught international relations at Saint Petersburg State University from 2004 until 2006.
From 2006 to 2012 Lange headed the CDU-affiliated Konrad Adenauer Foundation office in Kyiv.
From 2012 until 2017, Lange led the foundation's domestic policy team in Berlin.[2] In this capacity, he was appointed by CDU Secretary General Peter Tauber to a commission tasked with drafting proposals for reforming the party between 2013 and 2017.[3] In 2014, he chaired a task force on the future of political parties in Germany. He was also member of a CDU working group committee on domestic policy reforms. After the CDU lost elections in Baden-Württemberg in 2016, Lange accompanied the party's deputy chairman Thomas Strobl when he toured the state visiting local chapters and discussing with members.[3]
From 2017 until 2018, Lange headed the foundation's Washington office.
In April 2018 Lange became deputy general manager of the CDU, under the leadership of newly elected chairwoman Annegret Kramp-Karrenbauer.[4]
