The latest Des Moines Register poll showed the senator leading in Iowa for the first time, edging ahead of Biden, 22 percent to 20 percent, though still within the survey's 4 percent margin of error. And a new national Wall Street Journal/ NBC News poll finds Biden and Warren separating from the rest of the field. Biden is backed by 31 percent, Warren pulled in 25 percent, and Sanders, at 14 percent, was the only other candidates with more than single-digit support.