HEMPSTEAD, N.Y. – During Tuesday night’s debate here at Hofstra University, President Obama once again attacked Mitt Romney’s proposals by saying “the math doesn’t add up.”

Obama has a point — Romney will have difficulty balancing the budget by his second term while walling off roughly two-thirds of the budget from cuts, and cutting tax rates by 20 percent without touching popular deductions. But if Obama wants to be a stickler for math, that opens up his own tax and spending claims to more scrutiny. In reality, it is mathematically impossible to protect popular programs like Medicare, Medicaid and Social Security from serious cuts and avoid massive deficits merely by raising taxes on the top 2 percent of taxpayers. Yet whenever Obama touts his “balanced approach” to the nation’s debt problem, this is exactly the plan he describes.