Josh Barro continues what I hope is an ongoing series on what may or may not be Mitt Romney’s Secret Economic Plan. In the latest installment, Josh argues that Paul Ryan’s credibility with congressional conservatives could prove instrumental to the Secret Economic Plan’s success. Though I’m not sure I agree with Josh on the contours of the Secret Economic Plan, e.g., I’m skeptical about Romney’s openness to mortgage modification, though I think he’s right to think that he’d tread lightly on Medicaid, etc., I think he’s right to suggest that Ryan could prove a significant governing asset. Ryan speaks the language of movement conservatism fluently, which is why he’s been able to persuade the House GOP to embrace a highly controversial budget. That makes for a stark contrast with Mitt Romney.