Ben Carson has surged into a statistical dead heat with Donald Trump in the race for the 2016 GOP nomination, a new poll shows. According to an NBC/Wall Street Journal poll released Sunday, Trump still leads the race, with the support of 21% of Republican primary voters across the U.S., but Carson follows with 20% — well within the poll’s 6-percentage-point margin of error. Just weeks ago, Trump was still the clear front-runner but Carson has been steadily gaining on him since Trump’s average performance in the second Republican debate earlier this month. And just one month ago, in the...