The average American is more concerned about their own taxes than Romneys'.
If true then they'll vote against Romney's tax plan which will raise the taxes of an average American if it truly is revenue neutral as he claims.
This right here. The tax issue by itself won't hurt him. It juxtaposed with his tax plan, makes things go from bad to worse. The tax issue is defining Romney and his tax plan reinforces it.
Bingo. Probably the only policy difference that most Americans understand between Romney and Obama is that Obama wants to raise taxes on the rich and Romney wants to lower them. And raising taxes on the rich is popular with Dems and Indies (and even some Pubs). And Mitt Romney is Exhibit A for why the rich should pay more taxes.
All this debate is doing is reinforcing the notion that Romney is ultra rich and is getting a great deal on his tax rate, so much so he doesn't even want people to see how great a deal he is getting. He is therefore losing the ability to ever make the argument against raising taxes on the rich. It just look like he is trying to protect himself and his fellow ultra-rich.