The american people know that president Obama has broken the pledge he made. He said he wouldn't raise taxes on middle income Americans. Not only did he raise the $500 billion that was already in the bill. It is now clear that his mandate, as described by Supreme Court is a tax.
Mitt Romney talks about the individual mandate in Obamacare, and that since the Supreme Court has ruled it as a tax, he has broken the pledge he made not to raise taxes on middle income Americans.