Virginia's school superintendents took aim at a couple of Gov. Bob McDonnell's key legislative initiatives Tuesday, calling them unfunded mandates that would cause crippling budget cuts in local school divisions across the state. Particularly onerous, they said, is the Republican governor's proposal to pump an unprecedented $2.2 billion into Virginia's underfunded state retirement system. About half of that money would have to come from localities. The superintendents said virtually all Virginia school divisions would face drastic budget shortfalls as a result, leading to staff cuts, bigger classes and diminished quality of education.