Legislative staff have pegged the cost at $104 million per year by 2011. But the chamber's analysis called that figure "overly optimistic" and predicted it could cost much more and mean much higher payroll deductions for workers.
Supporters of family leave deemed the chamber's study a desperate attempt to halt efforts to help New Jersey workers.
"Legislators will see through this and vote to protect the interests of New Jersey's working men and women," said Jon Shure, speaking for the Time to Care Coalition, a group that backs paid leave.
The Senate is scheduled for a final vote on the plan on Monday. It was approved by the Assembly last month. Gov. Jon S. Corzine has said he'll sign it.
New Jersey would become the third state to approve paid leave, behind California and Washington.
The Democratic-sponsored plan would let workers take up to six weeks paid leave beginning July 1, 2009.
The leave would be funded by a payroll surcharge that would cost workers up to $33 a year. Workers could get up to two-thirds of their salary, up to $524, to care for either a newborn, newly adopted child or sick relative.
Business groups and Republican opponents contend the bill will hurt businesses and have labeled the payroll surcharge a new tax.
Under the New Jersey plan, parents could take paid leave any time in the first year after a child's birth or adoption.
People would be allowed to take paid leave to care for a sick relative who is receiving inpatient care in a medical care facility or under continuing supervision from a health care provider. A health care provider could also certify a sick relative needs help at home from a family member.
