She previously served as Deputy Assistant Secretary for Finance and Budget within the department as well as in various roles at the Federal Aviation Administration (FAA).

Wassmer served as the vice president of administration and finance at the Millennium Challenge Corporation from 2010 to 2011.

Wassmer was nominated by President Barack Obama to several positions in his administration, including the Environmental Protection Agency and Department of Energy.

[4] On March 26, 2021, President Joe Biden nominated Wassmer to be the chief financial officer and assistant secretary of transportation for budget and programs.

Wassmer's initial nomination expired at the end of the year and was returned to President Biden on January 3, 2022.