It's where the money is.

[The Rabbi]

Willie Sutton was talking about why he robbed banks.
But Obama is not talking about taxing the middle class. But he should be. Here's why:
Review & Outlook: Where the Tax Money Is - WSJ.com

This is politically risky, however, so Mr. Obama's game has always been to pretend not to increase taxes for middle class voters while looking for sneaky ways to do it. His first budget in 2009 included a "climate revenues" section from the indirect carbon tax of cap and trade, which of course would be passed down to all consumers. Such Democratic luminaries as Nancy Pelosi have often chattered about a European-style value-added tax, or VAT, which from a liberal perspective has the virtue of applying to every level of production or service and therefore is largely hidden from the people who pay it.

Now that those two ideas have failed politically, Mr. Obama is turning as he did last week to limiting tax deductions and other "loopholes," such as for mortgage interest payments. We support doing away with these distortions too, and so does Mr. Ryan, but in return for lower tax rates. Mr. Obama just wants the extra money, which he says will reduce the deficit but in practice will merely enable more spending.

More at the source.