“At the political futures market Intrade, shares in Mitt Romney have been a hot commodity this week. As of early Thursday evening, the bettors there gave Mr. Romney a 43.5 percent chance of winning November’s election. That’s up from about 39 percent late last week, before Mr. Romney’s announcement that Representative Paul D. Ryan of Wisconsin would be his running mate. Our forecast model has usually been more bearish on Mr. Romney’s chances than Intrade – but it also shows him gaining ground over the past several days. It now gives him a 31.3 percent chance of winning the Electoral College, up from 26.7 percent late last week.