Sanders separated himself from the pack in a New York Times-Siena Research poll of Iowa released over the weekend, one of the first to find a clear-cut leader in the Hawkeye State. And a WBUR survey of New Hampshire released this week found Sanders opening up a 12-point advantage over the next closest contender.

Sanders surpassed Biden in CNN’s latest national poll, marking the first time Biden has not held the top spot in that poll this cycle.