Just how high do Democrats/liberals/progressives want to raise taxes over the long run to pay for the level of government spending they desire? If you are going to spend like Europe, you need to tax like Europe. A helpful tax fact from the FT may provide a clue:
Including state and local government taxes, the US remains a low-tax nation compared with other developed countries, with revenue as a share of GDP of 24.8 per cent in 2010, compared with an average of 33.8 per cent for OECD countries.
So the average OECD tax burden is 36% higher than that of the US.
If you narrow the list down to the seven largest non-US advanced economies in the OECD, you get Japan, Germany, France, United Kingdom, Italy, Canada, and Australia,.Their average tax burden is a bit higher at 34.4%.