The Michigan Democratic Party announced Monday that it planned to file a complaint against the Michigan Republican Party and state Supreme Court candidate Colleen O'Brien over a "fraudulent" robocall that allegedly violated federal law.

The Michigan Democrats noted the automated message did not name the person responsible for the call or provide a telephone number as required by the Federal Communications Commission.

"Since the fraudulent robocall did not identify the organization that was responsible for the call as required by federal law, it's difficult to say who ultimately wrote the check for the call," Kirstin Alvanitakis, a spokeswoman for the Michigan Democratic Party, told Raw Story. "However, O'Brien and the Michigan Republican Party are the most likely suspects because they stood to gain the most from it."

The O'Brien campaign later admitted that it was behind the robocall, but insisted the automated message complied with federal law. The robocall urged Democrats to vote for O'Brien.

"Hi, my name is Amanda and I'm calling today to ask our fellow Democrats to support Judge Colleen O'Brien for Michigan Supreme Court," the automated message said. "Colleen O'Brien deserves our support. Remember the 'O' for O'Brien. Democrats should vote November 6 for Judge Colleen O'Brien for Michigan Supreme Court."

Judicial positions in Michigan are non-partisan. However, O'Brien was nominated to the ballot by Republicans -- not Democrats. Michigan Democrats nominated law professor Bridget McCormack, Southfield District Judge Shelia Johnson and Wayne County Judge Connie Kelley for the state's Supreme Court.

Both parties have spent millions to support their state Supreme Court nominees this year.

Alvanitakis said another robocall targeting Democratic voters urged them to cast their ballot for all three Republican-backed Michigan Supreme Court candidates. The automated message, which claimed to be from a Democrat, also did not identify who was behind the call or provide a telephone number.

[Woman on telephone via Shutterstock]

[Ed. note: Updated after publication]