In 2001, Keller joined the Green Youth and served as spokesperson of the Federation of Young European Greens from 2005 to 2007. From 2007 to 2009, she led the Green Party in Brandenburg having joined the German Green party in 2002. In Brandenburg, she campaigned for a statewide referendum against new coal mines.
Member of the European Parliament, 2009–present
During her first term (2009–2014), Keller served on the Committee on Development from 2009 to 2012. From 2012 to 2014, she was a member of the Committee on International Trade. In addition to her committee assignments, Keller was also member of the Parliament's delegation with the EU-Turkey Joint Parliamentary Committee. In this capacity, she focused on the issues of migration and the EU's relations with Turkey.
In her second term (2014–2019), Keller became co-president of the Greens/EFA group in the European Parliament in 2016. Additionally, Keller was a member of the Committee on International Trade from 2014 to 2017. She continued to serve as a member of the Delegation to the EU-Turkey Joint Parliamentary Committee and joined the Parliament's delegation to the Cariforum.[6]
From 2009 to 2011, Keller also served as member of the European Parliament's High-Level Contact Group for Relations with the Turkish Cypriot Community in the Northern Part of the Island (CYTR).[7]
In September 2022, Keller announced her resignation as co-chair of her party's group and her decision not to run again in the 2024 elections.[12]
Other activities
Institut Solidarische Moderne (ISM), Member (since 2010)[13]
Political positions
Keller is known for her commitment to fighting corruption in the European Union.[14] In February 2018, she participated in protests in Sofia against corruption in Bulgaria.[15]
In September 2019, European Commission President-elect Ursula von der Leyen created the new position of "Vice President for Protecting our European Way of Life", who will be responsible for upholding the rule-of-law, internal security and migration.[16] Keller said it was "scary to see a proposal for a portfolio on 'protecting the European way of life' which includes migration and border protection."[17]