Scott Walker just can’t make up his mind on birthright citizenship. “I’m not taking a position one way or the other,” Walker said in an interview with CNBC’s John Harwood. “I’m saying that until you secure the border and enforce the laws, any discussion about anything else is really looking past the very things we have to do.” Harwood then observed that Walker seemed threatened by Donald Trump’s hard-line stance on immigration, and was adjusting his rhetoric accordingly. On Sunday, Trump announced a $166 billion immigration plan that includes a nearly 2,000-mile wall across the U.S.-Mexico border, the deportation of...