Conversation so far:
When did Tammy Duckworth start her career in politics?
On November 21, 2006, several weeks after losing her first congressional campaign, Duckworth was appointed Director of the Illinois Department of Veterans Affairs by Governor Rod Blagojevich.
What did Tammy Duckworth do after working in the Department of Veterans Affairs?
On September 17, 2008, Duckworth attended a campaign event for Dan Seals, the Democratic candidate for Illinois's 10th congressional district.
When did Tammy Duckworth transition into other roles outside of the Department of Veterans Affairs?
Duckworth was nominated to be the Assistant Secretary of Public and Intergovernmental Affairs. The United States Senate confirmed her for the position on April 22, 2009. Duckworth resigned June 2011.

Question: Why did she resign?
Self-contained rewrite: Why did Tammy Duckworth resign as Assistant Secretary of Public and Integovernmental Affairs?