In what was billed as a “prebuttal” to President Obama’s Democratic National Convention speech in Charlotte this summer, Mitt Romney on Wednesday cast the incumbent as incapable of fulfilling the promises of 2008, saying “he’s in over his head and he’s swimming in the wrong direction.” In a week when Democrats have hammered Romney on transparency, Romney sought to refocus the political conversation on the economy, where polls show he holds an advantage over the president.