Keep one thing in mind when looking at the data from Gallup’s latest poll of the Republican field. Their sample includes “Republican-leaning independents†as well as registered Republicans. That’s important, because it helps explain Donald Trump’s sudden resonance in the field: Donald Trump debuts in a first-place tie in Gallup’s latest update of Republicans’ preferences for the party’s 2012 presidential nomination among potential contenders. Trump ties Mike Huckabee at 16%, with Mitt Romney close behind at 13%. Sarah Palin is the only other potential Republican candidate to earn double-digit support.The April 15-20 Gallup poll finds Trump leading the field among...