The Tax Policy Center has now analyzed the Santorum proposals for what the US tax system should be, and I have added the implied average tax rates to the above diagram for completeness. Santorum would cut taxes for almost all income groups by even more than his Republican colleagues, except for those making more than $1 million a year whom Gingrich and Perry would tax even less than Santorum.
But the result of all these tax cuts is that Federal Government revenues would fall by an estimated $1.32 trillion in 2015 alone. This is even higher than the $1.28 trillion in revenue losses under Gingrich. But total Federal Government discretionary expenditure, on everything, including the military, is projected to be only $1.26 trillion in 2015. The deficit would rise even if all this government expenditure were cut to zero (and you cannot cut to less than zero). Yet Santorum says the government deficit is already too high. He also says military spending should be raised, not lowered.
This is even less serious than the proposals of Gingrich.