Last Iowa Poll Before Caucuses Tells Us...

...not much, actually. It's being heavily promoted by the newspaper that commissioned the poll, the Des Moines Register, as being a fairly definitive summary of where the race stands, showing Barack Obama with a 7 point lead over Hillary Clinton (New Iowa Poll: Obama widens lead over Clinton) and Mike Huckabee with a 6 point lead over Mitt Romney (GOP poll: Huckabee maintains lead over Romney). But the Des Moines Register is also home to columnist David Yepsin, one of the best political columnists in the nation, and he tells us that if you look carefully at the poll numbers and responses, the race is a lot more in play than it appears (Yepsen: In newest poll, soft preferences and newcomers make a fluid mix). For example:

* Undecideds exist. There are 6 percent of likely Democratic caucus-goers and 4 percent of the Republicans who have no first choice. Their final decisions will be enough to change the order of finish in both parties. That fact alone should keep anyone from using these polls to forecast the outcome of the race.

* Last-minute developments won't be reflected. In 2004, 21 percent of those who showed up at Democratic caucuses decided who they'd support in the last three days of the campaign. This poll won't reflect those decisions because it came out of the field on Sunday night -- four days before people vote.

So, for example, it can't reflect the goofy press conference Huckabee held on Monday in which he promised not to run attack ads against Mitt Romney while producing them and showing them to reporters anyway. Right.

* Some support is soft. Of those who have decided on a candidate, 34 percent of the Democrats say they could still be persuaded to change their minds.
Among Republicans, it's 46 percent.

* A lot of caucus-goers are first-timers. A whopping 60 percent of the Democrats say this would be their first time at a caucus. Some 40 percent of the Republicans say that.

* A lot of Democratic caucus-goers aren't all that Democratic. Some 40 percent of the Democratic caucus-goers say they are independents, and another 5 percent say they are Republicans. (Technically, they'll all have to re-register as Democrats to participate, but that can be done at the caucus site.) Put another way, 54 percent of the Democratic caucus-goers say they're Democrats. In 2004, it was 80 percent.

It looks as if support for the candidates from both parties is much softer than one would think it should be at this late stage, especially on the Republican side, and there could be a heck of a lot of movement before Thursday - again, more so on the GOP side than the Dem side. Bottom line - who knows what's going to happen, but if I were Huckabee and Clinton I wouldn't rest easy...