When Gov. Chris Christie of New Jersey overhauled the state’s pension system in 2011, he celebrated it as a bold, bipartisan step toward paying down the state’s costly promises to its retired workers. Some would have to work longer, some would lose inflation adjustments, and both workers and taxpayers would have to pay more into the system.

All of that helped lower the retirement system’s overall costs, but the new system needed a lot more money right away and the law did not provide it. Instead, its eight-year schedule of steadily rising payments was not enough to cover the system’s true costs and stop it from sliding further into debt.

So just three years after the law took effect, Mr. Christie is again raising concerns about whether the state can afford the payments it had promised to make to its pension system. Under the schedule agreed upon, the state’s annual pension payments were to rise from zero in the first year to $1.7 billion this year, the largest the state has made to the system, yet still only about a third of what it will owe by 2018.

“We need to have the conversation now about further changes to our pension system,” the governor said in his State of the State address last month, contending that education and other needs would be shortchanged by the rising payments. “The time to avoid this conversation and avoid these choices is nearly over, everybody.”