While Hillary still has a big lead over the rest of the Democratic field, she is trending rapidly towards that dangerous territory — below the vital 50% threshold. Given the weakness and lack of funding for her Democratic opposition, it is tremendously significant that about half of the party’s primary voters in key early states do not vote for her.

In Iowa, the first contest, she has slipped from 60% on May 7 in the Quinnipiac poll to only 54% in the June 15th Morning Consult survey. That means, of course, that 46% of the likely Iowa caucus goers choose not to back her at this stage.

In New Hampshire, the drop is even greater. The Bloomberg/St. Anselm Poll of May 10th gave Hillary 62% of the vote among likely primary voters. But the June 15th Morning Consult poll has her down to 44% of the vote. In the Granite State, which powered her 2008 recovery from her Iowa defeat, 56% of the voters won’t back her candidacy. Now that’s very significant.

Even in South Carolina, where her support tis anchored by a large black vote, she draws only 56% of the vote in the June 15th Morning Consult survey.

The votes of those opposed to Mrs. Clinton are clearly fungible. A voter who backs Senator Sanders or Vice President Biden could vote for any of the Democratic alternatives. And undecided voters have, in effect, decided not to vote for Hillary. As the debates loom, when Sanders and the others will showcase their candidacies, the erosion in Hillary’s support will likely continue and even accelerate. Look for her to be under 50% in the post-debate polls, no matter how well she does.

At this point, there is a reasonable chance that she may not win Iowa or New Hampshire.

What happens then?

The Democratic Party will fly into a panic at the prospect of Bernie Sanders walking away with the nomination, just as they did in 2004 when fellow Vermonter Governor Howard Dean showed momentum in Iowa. The key Democratic operatives — Kennedy and Clinton people — hustled to John Kerry’s side to head off the Dean offensive. John Edwards, the third candidate, was pushed off to the side. Dean cracked under the pressure.

But Sanders is less likely to crack. His national experience spans several decades. And Hillary has only a very limited capacity to recover. Her massive credibility problems have essentially taken away her ability to speak. She can say what she wants, but nobody believes her. Even when she takes issue positions, voters realize that she is flip flopping in the heat of the primary and will probably say something contrary next month.

So the search for a real alternative nominee in the party will intensify, driven not only by Hillary’s downturn, but by the danger of Bernie Sanders as well.

Elizabeth Warren? Some other candidate? Biden? We’ll see.