Well that's just silly, California as a state can't really "withhold" tax money as they don't touch it. Companies withhold taxes from employee checks and submit it directly, along with any corporate taxes due. And not a single company would dare attempt to withhold federal tax money. Furthermore, the federal government controls the banks, thus they control the flow of money.
Also, the idea that the federal government would go broke if they lost 13% of their revenue is a bit silly. The US government would essentially lose about 100 billion (456 billion or so in revenue from CA, and about 350 billion in expenditures in CA). Also noteworthy that per capita revenue from CA is much lower than half the states - it's really only CA's population that gives the state a high contribution level.
Furthermore, California is a very dependent state. Water, power, food, fuel ....California only has enough of these things for their population because of all those silly "leech" states that Californians like to bitch about "supporting". Pretty much all states are dependent on all the other states. The closest any state gets to being able to be "independent" is Texas and that's because they spent a ton of money doing it - setup their own power grid (no other state has their own power grid that could power their state if disconnected from the national power grid).
