She became known as office manager to German Chancellor Angela Merkel and, alongside Eva Christiansen, as her closest advisor.
Baumann was already politically active during her studies, for example on the state executive committee of the Jungen Union in Lower Saxony.
On the recommendation of Christian Wulff, Baumann became Angela Merkel's advisor in the Federal Youth Ministry in January 1992 and moved with her to the Federal Environment Ministry as office manager in 1995.
Merkel's decisions to run for the chancellorship again in 2017 and to vote against Marriage for All had to be supported by her as office manager, but she was personally of a different opinion.
After the end of Merkel's chancellorship, she told Spiegel that she was working on a biography with her, which would be published in November 2024.