NEW YORK (Reuters) - New Jersey's State Supreme Court said on Friday it would hear a challenge to Governor Chris Christie's plan to hold a special election in October to fill the U.S. Senate seat left vacant by the death of Senator Frank Lautenberg.
The state's highest court said a group of Democrats have until Monday to file a motion seeking to overturn a lower court ruling that Christie acted within his authority when he called the special election.
Christie set the special election for October 16, three weeks before voters head to the polls for the November 5 general election in which he is seeking a second term.
"It's going to be chaos and confusion," said Somerset County Democratic Party chairwoman Peg Schaffer. "It's two registration deadlines. Two mail-in vote deadlines, two sets of ballots. It's just unnecessary."
Democrats believe the Republican governor called the special election to avoid appearing on the ballot in the November election at the same time as popular Newark Mayor Cory Booker, a Democrat.
Booker is currently the front-runner for Democrat Lautenberg's seat, according to a Quinnipiac poll. His candidacy was expected to bring a large number of Democrats and minorities to the polls, potentially tightening Christie's race against Democratic challenger Barbara Buono.
Schaffer said holding two elections will likely suppress voter turnout at the general election by about 10 to 12 percent.
"That's bad for everyone, but it's historically bad for us," the Democrat said.
The governor's office expressed confidence the Supreme Court would uphold the lower court's decision.
"Governor Christie followed the law as established by the legislature and ensured New Jersey voters would have a voice and a choice - in both a primary and general election - in selecting the next U.S. senator for New Jersey," said Christie spokesman Michael Drewniak.
Christie could have filled Lautenberg's seat through the end of his term next year, but instead designated former Attorney General Jeffrey Chiesa, a Republican, to hold the seat temporarily until a new election could take place.
The special election, which includes an August primary and the October balloting, will cost $24 million to administer.
The high court's decision was expected as early as next week.
(Editing by Barbara Goldberg and Jackie Frank)