A special U.S. Senate election to replace the late Democratic Sen. Frank Lautenberg can be held in October, as it was scheduled by Republican Gov. Chris Christie, a state court ruled Thursday.

The ruling could be appealed. And while it keeps an election on course it does not seem likely to chill criticism of the popular governor for how he chose to replace Lautenberg, the Senate's oldest member, who died last week at age 89.

Four Democrats and two Republicans have filed petitions to run in the Senate race to complete Lautenberg's term, with three early polls showing Democratic Newark Mayor Cory Booker as the front-runner.

Christie scheduled the election for Oct. 16. A group of Democrats sued, saying it should be held Nov. 5, the day voters are going to the polls in the general elections anyway.

Christie's critics have complained that holding the election in October will cost taxpayers unnecessarily. Officials say each election costs the state about $12 million to run.

Judge Jane Grall wrote Thursday that objections to the costs of the election are policy matters that aren't questions for the court.

"The question for us is whether the date selected is in violation of the law or Constitution, and we conclude that it is not," she wrote.

Christie spokesman Michael Drewniak said the governor "followed the law as established by the legislature and ensured New Jersey voters would have a voice and a choice" in selecting the next U.S. senator.

Somerset County Democratic Party chairwoman Peg Schaffer, a lawyer for a group of Democrats that sued, said she would speak with other groups involved in the litigation to decide whether to appeal to the state Supreme Court.

Democrats have said Christie did not want his re-election vote and Legislative elections he's hoping his party wins on the same ballot as Booker, who, like Christie, is a nationally known figure. One of their fears is that voters will not turn out for one election in October and another in November.

Some conservative Republicans say Christie should have appointed someone to serve the rest of Lautenberg's term, giving Republicans a better chance to hang on to the seat after the term expires in January 2015.

Instead, Christie appointed former state Attorney General Jeffrey Chiesa to the Senate, but only until a replacement can be elected. Chiesa, a Republican and confidant of Christie, is not seeking the seat beyond the short stay.

Christie has said he wants voters to be able to decide who represents them and for that democratic say to happen as soon as possible.

The governor taped a humorous bit defending his position for NBC's "Late Night with Jimmy Fallon" on Wednesday. The show was bumped by a triple-overtime NHL playoffs game, but the video, in which Christie slow-jams the news, was made public Thursday.