Marybeth Feiss, 42, of Fort Lauderdale, faces a maximum of five years in prison. She pled guilty to conspiracy to violate the Federal Election Campaign Act and defraud the United States, according to the department.
While at the firm, Feiss organized events and collected campaign contributions.
Rothstein asked Feiss and other employees to make political contributions to campaigns so that the firm could bypass the limit that donors are allowed to contribute, the department said.
The employees were then reimbursed by the firm.
Feiss' sentencing is scheduled for May 4.