Kinde Durkee heads to court next month, accused of stealing money from campaigns of several elected officials.
According to a federal complaint, investigators found substantial sums were routinely placed into her company accounts or channeled to other campaigns, apparently when suspicions were raised about missing money.
Politico.com reported that Feinstein said her campaign was wiped out, and the losses could run into the millions.
Rep. Susan Davis was also a client. She lost about $250,000 and believes Durkee could become the Bernie Madoff of her profession.
Federal prosecutors say Durkee siphoned off nearly $700,000 from a California candidate to pay her credit cards, a mortgage and business bills.
A complaint outlines an elaborate shell game in which Durkee furtively shifted money out of state Assemblyman Jose Solorio's 2010 campaign to pay for an array of debts, from shopping at Costco to her mother's care at an assisted-living facility.
Lauren Horwood, a spokeswoman for the U.S. attorney's office in Sacramento, said more charges are likely.
The Associated Press contributed to this report.