Reported here:
"But the full plan includes one very significant change not mentioned in the Wall Street Journal op-ed where Bush announced his plan—one that would likely raise more than a trillion dollars in revenue over a decade, and secretly accomplish a policy goal sought by everyone from President Obama to Paul Ryan. The change: Bush wants to limit itemized deductions sharply, capping them at 2 percent of aggregate gross income, and eliminate the deduction for state and local taxes entirely. (The exception would be the deduction for charitable giving, which is politically toxic to attack, and would still be unlimited.) ...
"But it’s the politics of the cap that make it really interesting. If you look at who would actually be affected, it appears that the cap is a very benign-sounding way to do something politically difficult: limit the mortgage-interest deduction. Of the $54 billion a year the cap would raise according to the Feldstein estimate, $46 billion comes out of the mortgage interest deduction."