One of the biggest challenges facing lawmakers in the current tax reform process is finding a way to reduce headline tax rates in a revenue neutral way. Some revenue raisers (like eliminating itemized deductions) would raise significant revenue and simplify the tax code. Other revenue raisers come at the cost of increased complexity, at least in the short term (e.g., implementing a federal VAT or a new carbon tax). Closer inspection of ideas on the table reveals that politically popular reforms are not necessarily the largest revenue raisers. For example, there seems to be bipartisan support for taxing carried interest as ordinary income (more on that here), a relatively small revenue raiser. But the big ticket revenue raisers (like eliminating the deduction for net interest expense or implementing border adjustments in the move to a territorial system) are very controversial.
The revenue raising power (or lack thereof) of various recent proposals is graphically illustrated below, where we compare the revenue estimated to be raised over 10 years by some of the most frequently mentioned proposals.