Washington (CNN) -- A Nevada group supporting a change in how judges in the state are selected has apologized for political "robocalls" featuring retired Justice Sandra Day O'Connor, which were mistakenly sent out in the middle of the night.
Nevadans for Qualified Judges admitted about 50,000 residents received the automated phone calls between midnight and 1:15 a.m. Monday. The non-profit organization blamed a California marketing firm for the mistake.
O'Connor has been an active supporter of Proposition One, a proposed constitutional amendment that will appear on Tuesday's statewide ballot. The jurist said Wednesday, however, that she had not agreed to allow her voice to be used on the telephone calls, a common political campaign tactic.
The amendment would switch the current system for choosing judges away from contested elections to a merit-based system. Candidates would be nominated by a blue-ribbon citizen panel, with the governor making the final choice for vacant seats on state district and supreme courts. Judges would then be subject to public evaluations and periodic up-or-down retention elections.
The legislature approved the change in recent years, but the referendum must now be OK'd by voters.
State officials and local media were bombarded with complaints from angry call recipients. The Carson City-based Nevada Appeal reported one of those awakened was an official in the Secretary of State's Elections Division.
"I was one of the people who got that call," said programs officer Kristi Geiser. "At 1:05 a.m."
O'Connor, 80, is heard on the taped call urging support of Prop One. "When you enter a court the last thing Nevadans want to worry about is whether the judge is more accountable to a campaign contributor or to a special interest group than to the law," she says. A narrator then urges listeners to back the measure.
Similar television ads -- both in English and dubbed in Spanish -- feature O'Connor addressing voters on camera. They have appeared online and in some local media markets.
The sponsor of the calls sent follow-up robocalls later in the day, explaining their human and computer error.
"We sincerely apologize to many Nevada voters who received an automated telephone message after hours last night," said Greg Ferraro, a member of Nevadans for Qualified Judges, in a subsequent statement. "The company that was hired by Nevadans for Qualified Judges to execute the phone calls, Stones' Phones Inc. in Rancho Mirage, [California], mis-programmed the time of day for the calls. There is no excuse for this to have happened and the NQJ campaign is very sorry for your late night interruption."
But O'Connor, who was the first woman to serve on the Supreme Court, issued a statement saying she had not authorized the use of her comments in robocalls.
"I did not authorize the use of my recorded statement as part of automated telephone calls to Nevada residents, and I regret that the statement was used in this way," she said. "In addition, I view my efforts in support of judicial reform as consistent with the Code of Conduct for U.S. Judges."
Conservative legal groups expressed deep concern over O'Connor's continuing involvement in such a hotly contested "political" issue. Although retired from the high court since 2006, she remains on "senior status," allowing her to sit on cases argued before federal appeals courts.
She was part of a divided three-judge panel that ruled Tuesday against Arizona's effort to require proof of citizenship and other identification in order to resister to vote or cast a ballot.
The 9th Circuit U.S. Court of Appeals, by a 2-1 vote that included O'Connor, said that state initiative violated the National Voter Registration Act. The goal of the federal legislation was to enhance voting opportunities for American citizens by making it easier to register to vote and to maintain one's registration.
Conservative activist Ed Whelan said O'Connor's dual role as a judge and "political activist" violates federal codes of conduct.
"I see nothing in it that would plausibly be read as authorizing a judge to campaign in support of a ballot initiative," he wrote on his Bench Memos blog at National Review Online. "If O'Connor wants to continue her unseemly politicking on state judicial selection, she should fully and unmistakably retire from the bench. Pronto."
The Code of Conduct for United States Judges says that "a judge should refrain from political activity," but does allow a judge to "participate in ... activities concerning the law" and "consult with or appear at a public hearing before an executive or legislative body or official."
The conservative Judicial Crisis Network said Nevadans for Qualified Judges is backed by liberal activist and billionaire George Soros. The Judicial Crisis Network questioned whether the justice was being paid by the pro-Prop One group for her support.
"O'Connor no doubt understands the game she is playing by joining forces with George Soros' legal lap dogs, but she has made a calculated decision to be a political leader now, destroying her ability to act as a neutral arbiter of the law," said Judicial Crisis Network's executive director, Gary Marx. "I call upon her to immediately resign her federal judicial post. Justice O'Connor must be transparent with the taxpayers who pay her salary and with the American public that deserves a judicial system made up of neutral arbiters of the law not political activists."
O'Connor has made judicial independence and election reform for judges a major part of her post-retirement activities. She has spoken out if favor of changes in how judges are selected, including in Iowa, where three supreme court justices are up for a retention election. That court was criticized for a unanimous ruling last year allowing same-sex marriage in the state.