In the 2012 presidential election, there was a lot of debate about our current personal income tax system. On the one hand, President Obama wanted to keep Bush era tax cuts when they expired at the end of 2012, except for family making over $250, 000. For these families, their highest marginal tax rates would increase from 31%, 33% and 35% to the pre-Bush era tax rates of 33%, 36% and 39.6%. On the other hand, Mitt Romney, the Republican presidential candidate, wanted to cut tax rates further for all family from the current tax rates and expand the income tax base to make up for the revenue loss by eliminating tax loopholes such as deductions and credits, although without specifying what they are.
What are the economic rationales for these two tax plans of the two parties?