New Jersey could be downgraded again because of its growing budgetary imbalance and underfunded public pension, Standard & Poor's Ratings Services warned on Monday.

S&P had already cut the state's rating to "A+" in April. Wall Street's two other main credit rating agencies soon followed in slicing the state to a single-A rating. That put New Jersey among the three lowest-rated states, along with California and Illinois.

S&P will resolve its negative creditwatch in 60 to 90 days following the outcome of state budget deliberations, it said on Monday. New Jersey Governor Chris Christie said on May 20 that he plans to slash pension contributions after having to reduce revenue projections by at least $2.7 billion through fiscal 2015.