There is a CBO study that shows there is no significant correlation between marginal income tax rates and the growth of GDP. In fact the report goes on to show that the biggest effect of lowering marginal income tax rates was the concentration of income at the top.
I’ll try and find the link again.
Correlation is not causation. Economics is diabolically difficult to figure out. If you assume that the government does not waste too much money (including buying votes), and that actually helps the economy in the long run, you would argue that "big government" is a good thing, and use Clinton (even though he said the era of big gov is over) as evidence that raising taxes does not necessarily hurt the economy.
Although GWB was a failure, I think the Obama presidency has been much worse. Although I can understand voting for neither Romney nor Obama, I can't imagine voting for such scum as the latter. I am ashamed of the people who voted for him.