Barely a week into his 2012 presidential campaign, Rick Perry has already assumed the mantle of the de facto Republican front-runner, emerging in the latest Gallup national poll with a huge, 12-point margin of support over Mitt Romney. The poll, conducted Aug. 17-21, found that 29% of Republicans and Republican-leaning independents now support the Texas governor, compared with 17% for Mr. Romney, 13% for Texas Rep. Ron Paul and 10% for Minnesota Rep. Michele Bachmann. “Perry’s official entry has shaken up the Republican race, making him the new leader for the party’s nomination,” the Gallup poll concludes. The survey found...