For thirty-five years Billi has been active in the Vermont Democratic Party, serving on the Brookfield Democratic Town committee, on the Orange County Democratic Committee, and on the Democratic State Committee. She was awarded the first David W. Curtis Leadership Award in 1999. She has attended every Democratic National Convention since 1984, twice as a page and seven times as a delegate. In 2004 she was chair of the Vermont electors for the Electoral College. That same year she was elected to serve as Democratic National Committeewoman, and was re-elected in 2008 and 2012.