First of all, Democrats have mostly been supportive of tax increases more recently. They opposed the Bush tax cuts, supported Bill Clinton's tax increases, and have proposed numerous other ideas such as the carbon tax and tax on high end insurance policies. The truth of the matter is: Democrats would raise our taxes if presented with the opportunity to do so.
Now I agree with Paul Krugman in that I believe that the Republicans don't oppose taxes because they believe in "fiscal responsibility". The Republicans realized in the 1970s that they could not cut spending on Social Security, Medicare and other popular programs without facing a massive public backlash. At this point they began a strategy that deprived these programs of funding so the government would be forced to eliminate them. And how could they go about cutting spending? By cutting taxes.
Clearly the Republicans are winning the messaging war over the tax issue. When you have Democrats bragging about cutting taxes, clearly there has been a paradigm shift in America. But there is a difference between the parties on this issue. The Democrats have cut taxes on the middle and lower class whereas the Republicans have cut taxes for the wealthy. Liberals, including myself, have always argued that the wealthy should pay the most taxes because they have the ability to pay them. Also, depriving the upper classes of inherited wealth leads to increased social mobility, hence the American dream.
So the next time the Republicans say they want to cut taxes, lets ask them whose taxes they want to cut and for what purpose. As far as the Democrats go, the middle class should not see their taxes go up disproportionately under Obama though everyone will have to help bring down our deficit.