NEWPORT BEACH, Calif.—Rancho Santa Margarita Mayor Carol Gamble pleaded guilty Friday as expected to a misdemeanor charge related to her nominating petitions and was ordered to perform 160 hours of community service.

Gamble turned in nominating petitions for her reelection to the City Council that violated the law because she did not personally witness the signatures, prosecutors said. If she is reelected Tuesday, she cannot take office and the city will have to hold a special election, prosecutors said.

Her attorney, Paul Meyer, characterized the situation as a mistake and said she immediately agreed to cooperate with law enforcement.

“As soon as she learned of the error, she contacted the city to correct it,” he added. “The law did not allow a correction. She consulted two expert election attorneys who confirmed that the law does not permit correction at that time. She had her lawyer notify the [District Attorney’s Office] of her decision to admit the mistake and to resign if elected.”

Meyer pointed out that officials “who learned of the error held the information until the deadline for correction had passed. That was their right to do so. Such is politics in today’s world.”

Gamble “issued a statement admitting her error. She voluntarily agreed to return all her contributions, and has done so,” Meyer said. “She said she would resign if elected. None of that is required by today’s plea. It is all voluntary.”

Meyer said Gamble is “embarrassed,” and added that she “is a wonderful and respected woman who devoted decades to create and grow a city she loves. She appreciates having been able to work overtime for decades in service. She thanks everyone for the huge outpouring of support, and shock at the way the law works here.”

Prosecutors said Gamble, a four-term mayor, agreed to plead guilty to a misdemeanor, perform 160 hours of community service and serve one year of probation.

“American democracy relies on the absolute integrity of the electoral process,” Orange County District Attorney Todd Spitzer said in a statement. “Voters must have total confidence that every election is being carried out in a fair and unbiased manner. Interference in the electoral process in any manner and at any stage jeopardizes the will of the people being carried out while eroding the trust of voters that their vote counts.”

Spitzer added, “I refuse to allow our electoral process to be subverted and exploited by anyone. The decision to file criminal charges against the candidate prior to an election is not a decision I made lightly but given the risk to the electoral process as well as the potential of the city of Rancho Santa Margarita having to pay for a special election should Gamble be re-elected, there was no choice but to file criminal charges prior to the election and alert voters of her ineligibility to run for City Council.”

Fullerton City Council candidate Scott Edward Markowitz pleaded guilty earlier this month to a misdemeanor for the same crime and was sentenced to 160 hours of community service.