For Mitt Romney, the stakes have never been higher. “If Romney cannot win Michigan, we need a new candidate,” a top GOP senator told ABC News. Politico’s Mike Allen reported that top Republicans are “poring over filing deadlines” in primary states and are devising a plan that would allow a new candidate to enter the Republican primary, in the event that Romney loses his home state. Enter Michigan Republican governor Rick Snyder. Snyder, who endorsed Romney this week, brushes off Romney’s lagging poll numbers, describing the situation as “very fluid.” “I think it’s still fairly early in the process,” Snyder...