The Bernie Sanders moment does not appear to be passing, at least not yet. The latest Quinnipiac poll of of likely Democratic caucusgoers in Iowa shows the Vermont senator trailing Hillary Clinton by 19 points—a gaping deficit, until you consider that just two months ago, Clinton led Sanders by 45 points in Quinnipiac's Iowa poll. Sanders has improved his position in Iowa, from 15 percent support to 33 percent, but Clinton's support has eroded, too; the former secretary of state was at 60 percent in early May, and now she's just holding onto a slim majority at 52 percent.

The direction isn't positive for Clinton, but the RealClearPolitics average of polls still shows Clinton is dominant in Iowa and nationally.The same can't be said for New Hampshire, where Sanders is within single-digits in one poll. According to the Real Clear Politics average of New Hampshire Democratic primary polls, Sanders has 31 percent support to Clinton's 46 percent. 

There are signs Clinton allies are taking Sanders seriously. Maria Cardona, a former Clinton operative and Democratic strategist, suggested on TV recently Sanders could win both Iowa and New Hampshire. She claimed his challenge was "good for the Democratic party" and would make Clinton a "stronger general-election candidate." And a super PAC with ties to fellow Democratic candidate Martin O'Malley (who is struggling in the polls) has taken to attacking Sanders, not frontrunner Clinton, for not being liberal enough on guns.

Meanwhile, Sanders appears to be exciting the progressive base that dominates the Democratic primary. Reports from a campaign rally in Madison, Wisconsin, Wednesday claim the 10,000-seat arena where Sanders called for a "political revolution" was nearly full. The 73-year-old democratic socialist has a movement on his hands. Can he sustain it?