Critics of Gov. Chris Christie’s decision to have a special election Oct. 16 to choose a U.S. senator contend that it will create a lot of unnecessary difficulties for voters and county election officials. By opting not to have the event 20 days later, as part of the general election for state and local offices, they say, Christie has created conditions for a perfect storm: voter turnouts even smaller than the embarrassing numbers in the high 40s that are normal in New Jersey, shortages of equipment and trained personnel, and, finally, contested results. And all that on top of the extra $12 million the decision not to combine the two elections will cost the state. The governor and his circle dismiss these complaints. He had full legal authority to schedule the election when he did, they say, and he did it lawfully and for appropriate reasons. That doesn’t diminish the potential for problems, which are substantial. One factor is what the Somerset County Democrats, in a lawsuit to overturn Christie’s decision, called “a confusing patchwork of registration and voting dates, including the highly irregular placement of an election on a Wednesday.” The lawsuit was rejected last week by the Appellate Division.