Here is some research that shows tax receipts are a more or less fixed fraction of GDP regardless of the tax rate. To get more revenue, increase GPD. That sounds like supply side economics, so Democrats won't like it. Besides, Democrats don't want more revenue, they want to re-distribute wealth.

http://www.theneweditor.com/index.php?/archives/8036-You-Cant-Soak-the-Rich.html