Wenzel was a Green Party delegate to the Federal Convention for the purpose of electing the President of Germany in 2009 and 2017.

As one of the state's representatives at the Bundesrat, he served as chairman of the Committee on the Environment, Nature Protection and Reactor Safety.

In 2014, Wenzel led the negotiations on the future of controversial radioactive waste disposal facility in Gorleben.

[4] When the Green Party had to leave the coalition government following 2017 state elections, Wenzel was succeeded by Olaf Lies.

[6] In October 2024, Wenzel announced that he would not stand in the 2025 federal elections but instead resign from active politics by the end of the parliamentary term.