At 74 years old, Vermont Sen. Bernie Sanders is the oldest major-party candidate in the 2016 field. But his rise in the polls this summer was powered by younger voters. Those voters aren’t likely to be a strong enough force to propel him to the nomination, but their support could give Mr. Sanders an important role in the election even after the primary is over.
In Iowa and New Hampshire, Mr. Sanders’s greatest gains, by far, have come among voters under the age of 45, according to NBC News/Wall Street Journal/Marist polls in those states.

Mr. Sanders’s appeal with younger voters is also apparent in the most recent Wall Street Journal/NBC News national survey. In that poll, the Vermont senator’s greatest strength lay with voters between the ages of 18 and 34. Some 45% of those voters viewed him positively, and only 18% viewed him negatively. The numbers for him grew less favorable among older age groups.