Recall that Romney paid more than he was obligated to just to get his tax up to 13%. And that’s just on AGI, and doesn’t include appreciation in his Sep-IRA fund which has magically accumulated $20 to $100 million despite the small cap on contributions.
13% is an interesting tax rate – it’s about what the working class pays just for their federal payroll taxes even with the temporary 2% stimulus cut, and even when their income tax is zero.
If you think the Marxists with pitchforks are going to get Romney’s tax rate anywhere near 40%, I’ll ask what you’ve been smoking! 
Would 25% be “class warfare”? How about 28%?
What is class warfare is to call the push for increasing taxes on the rich “class warfare” while insisting that the working class, who already pay a higher rate than Romney when payroll (and employer-provided) taxes are included, should pay yet even more so they have “skin in the game.”
Right now, Romney and lowest-wage workers pay about the same, about 13% each. Do I understand that you want to drop Romney’s rate to 10% while increasing the rate on lowest-wage workers (payroll tax plus income tax) to 23% ?