Kerry's drop in the New Hampshire tracking polls just touched statistical significance, dropping from 14% at the beginning of the month to 10% now, while Dean's drop is also flirting with significance (39%-35%) and Clark has made a strong and measurable surge (12%-21%). The nut graf from today's tracking poll, laying out the most serious problem facing Dean as the spectre of a meaningful Democratic convention (where at least two candidates are battling for the slot) looms:

Likely Democratic primary voters saying they will vote for Kerry or Lieberman are more apt to have unfavorable opinions of Dean. Of the 10% saying they will vote for Kerry, 17% have a favorable opinion of Dean and 75% have an unfavorable opinion of Dean. Of the 8% saying they will vote for Lieberman, 31% have a favorable opinion of Dean and 46% have an unfavorable opinion of Dean.

While we're at it, here's the critical piece from yesterday's tracking poll (covered by TPM) dealing with possible Dean-ish dirty tricks:

Over the past 2 days of calling, a number of older respondents registered as undeclared voters have reported that they have recevied telephone calls from a campaign informing them that they will not be allowed to vote in the Democratic primary because they missed the deadline to switch parties. A respondent discovered, however, that when she told the caller that she was thinking about Howard Dean, the caller told her that she would be eligible to vote.

So, someone's running a push-poll stamp-out-the-vote (SOTV) action to reduce turnout amongst a demo that Dean isn't particularly strong in. It could be led by either the GOP (who really wishes to face Dean, of course), or by Dean -- but it's more likely to be a rogue precinct or group within either of those organizations. In any case, coupled with the discovery of Dean infiltrators in Kerry's camp and allegations of a Dean plan to stuff the Iowa caucuses with out-of-state Deanies (thank you, Dan Savage), this could cause some heartburn for the Big Dean Machine.

However, Tom Harkin's surprise endorsement of Dean -- which also managed to take the edge off some unfortunate revelations from the Dean of 2000 -- will probably go a long way to restoring momentum to Dean in Iowa. (I left Iowa just before the Harkin news broke, so I can't say how it's playing there, but Harkin is essentially viewed as the corncob kingmaker.)