The Congressional Budget Office yesterday released The Deductibility of State and Local Taxes.  Here is part of the Preface:

This CBO paper, which was prepared at the request of the Ranking Member of the Senate Budget Committee, examines the arguments for and against the state and local tax deduction; how the benefits from the deduction are distributed among different groups of taxpayers and different governments; how the deduction and the AMT interact; and how modifying or eliminating the deduction would affect the federal budget, the finances of state and local governments, and federal taxpayers. In accordance with CBO’s mandate to provide objective, impartial analysis, the paper makes no recommendations.