Senator BIRMINGHAM (South Australia) (14:33): Mr President, I ask a further supplementary question. Will the minister explain, then, why any Australian should believe Labor's claims of returning to surplus when billions of dollars in carbon tax expenditure are unaccounted for and even the government and the minister himself will not guarantee that the carbon tax will erode their wafer-thin future surpluses? Senator Wong interjecting— Opposition senators interjecting— The PRESIDENT: On both sides! Senator Birmingham, you have asked a question of the minister. For those on my right and my left to be carrying on a debate when the minister is standing and waiting for the call makes it very difficult indeed.