During the 2012 election cycle Democrats are positioning themselves as the “defenders of the middle class,” and Sen. Bob Casey Jr. is honing that message by attacking the top .001 percent of income earners, including Facebook co-founder Eduardo Saverin.

Along with NY Sen. Chuck Schumer, Casey is introducing a bill that would prevent U.S. citizens from renouncing their citizenship in order to avoid taxes.

The legislation was sparked by Eduardo Saverin, a co-founder of Facebook, who renounced his U.S. citizenship in September to avoid paying $67 million in taxes he would owe when Facebook goes public.

In a press release Senator Casey’s office mentioned Saverin by name when describing the bill.

“(Senators Casey and Schumer are to) unveil a comprehensive plan to respond to Facebook co-founder Eduardo Saverin’s scheme to renounce his U.S. citizenship in order to dodge taxes on profits he is expected to collect when the social-networking company goes public.”

Saverin changed citizenship because Singapore, his new country of residence, does not have a capital gains tax.

In Singapore, Saverin has a reputation for living a lavish lifestyle, running up tens of thousands of dollars in bar tabs and partying with supermodels.

In addition to forcing ex-U.S. citizens to pay taxes, Casey’s law would prevent expatriates from reentering the U.S. if they renounce their citizenship.

The legislation has found some detractors. Dan Mitchell from the CATO institute likened the legislation to the “exit tax” imposed by German Nazis and Soviet Communists on departing Jews. And Timothy Burns, a tax lawyer in Hong Kong, warns that it will discourage international business owners from applying for dual citizenship.