McCain's criticism has apparently forced Obama to change his tax plan. From ABC News:

Facing criticism from John McCain that his tax plan constitutes "welfare," Barack Obama recently added a work requirement to one of his proposals.

"They started saying this was welfare," said Obama adviser Austan Goolsbee. "So, just so they would absolutely not be able to say that, we decided that for the last two percent we'll simply add a work requirement."

Goolsbee discussed the change to Obama's universal mortgage credit while debating McCain adviser Douglas Holtz-Eakin at the Council on Foreign Relations on Tuesday.

The purpose of Obama's 10 percent universal mortgage credit is to aid taxpayers who do not itemize when filing taxes. The Obama campaign estimates that it would provide an average of $500 to 10 million homeowners, the majority of whom earn less than $50,000 per year.