"What has come to light in our investigation is that the reimbursement for [Sebelius's] campaigning wasn’t properly filed by the DNC," said Cause of Action Executive Director Dan Epstein. "The FEC has an obligation to investigate and take appropriate measures to enforce their own rules."
In September, federal investigators found Sebelius guilty of making "extemporaneous partisan remarks" during a speech at a Human Rights Campaign gala last February. The comments amounted to a violation of the Hatch Act, which bans some political activity by government employees, the Office of Special Counsel said.
The White House responded by saying that the U.S. Treasury was repaid and Sebelius "met with ethics experts to ensure this never happens again."
The incident prompted criticism from Republicans, and Cause of Action slammed President Obama on Wednesday for giving Sebelius "a pass on the most high-profile Hatch Act violation in history."
The group called on federal investigators to probe the actions of a Sebelius aide, A.J. Pearlman, for whom the DNC also reimbursed some expenses.