Income splitting would act against the government's goals of reducing its debt more rapidly, if that is the government's goal. Income splitting is relatively expensive. It's in the neighbourhood of $2.5 billion to $3 billion a year at the federal level. It's about half that at the provincial level, from studies that have been done previously.
So it would be quite expensive, which would mean that if the government wants to maintain its path toward a balanced budget in a certain year, let's say 2015-16, then it would have to cut those expenditures someplace else out of the budget to make room for this tax expenditure of income splitting.