Texas Gov. Rick Perry may not have formally declared his presidential candidacy yet, but bettors on the news-futures website Intrade already are giving him the same chance of becoming the 2012 Republican nominee as former Massachusetts Gov. Mitt Romney, the presumed front-runner. Mr. Perry’s nomination odds reached a high of 33 percent Thursday morning, eclipsing Mr. Romney for the first time. Mr. Romney, trading at 32 percent, had been Intrade’s 2012 favorite since betting on the GOP nomination began in 2008 and had even consolidated his front-runner status in recent months as his opponents stumbled and other would-be challengers opted...