Would Democrats really vote for a tax increase?

President Obama has been (he hopes) scoring political points by painting the Republicans as intransigent about tax increases (excuse me, "revenue enhancements"). But as several commentators have pointed out over the past few days, even if President Obama had managed to get tax increases into a compromise package, it is not at all clear that enough Senate Democrats would vote for tax increases for it to pass. See, for example, Todd Lindberg's piece Could the Senate Even Pass a Tax Hike?