The Centrality of Iowa
    The key thing that has happened over this Summer which may or may not have been inevitable but which is now a fact is that, a Clinton win in Iowa would now certainly win her the nomination and probably going away.  However it is also clear that Iowa and particularly and Iowa Caucus is her weakest point anywhere in the country.
      Lets assume Hillary has a 20-point national lead that is around the statistical average, and lets also assume that Iowa is tied. This means that where the race is the most engaged the race is tied.  While Clinton fans might argue based on the RCP average that she is 4 points ahead, for an Iowa Caucus that is a for all intensive purpose a tie.  
    We have also seen a steady if not sharp decline in the trend for John Edwards's support in Iowa, as confirmed by the most recent Des Moines Register poll.  Edwards's fans might argue for a three-way tie, but it is fair to say that Edwards has now slipped to a close third.  
    While Clinton is up 20 nationally she is tied in Iowa. A brief history can explain why the Clinton Campaign probably never wanted to play here in the first place and why an Obama victory in Iowa is in fact sufficient to overcome this current as well as most future National leads.  

The Vilsack effect.
    It is entirely possible to believe that Tom Vilsack had every intention of running a very serious Presidential campaign, then decided he couldn't raise the money, quit the race, and then about a month later decided that Hillary was the best candidate and endorsed her.  If you are a Clinton fan that is a way to view history. It is however not the one that is the most accurate, Iowa particularly, Iowa Democrats have never been a source of particular Clinton strength.  In 1992, Iowa Senator's Tom Harkin's campaign for President prevented the Iowa caucus from playing their usual role as an important decider as he basically made the state no competitive.  When looking at the field of candidates in say September of 2006, before the Obama entrance, you were talking about the current field, plus Warner Bayh, Kerry and Feingold.  Based on what we now know about Hillary's strengths but her weaknesses in Iowa, Tom Vilsack was I believe planning to darkened Iowa for her in the same manner in which Harkin darkened it in 1992.  This would allow Clinton to withdraw from Iowa, not out of weakness, but out of "my respect for the Job Tom Vilsack has done for the people of Iowa."  This would have posed huge problems for the rest of the field because and this is particularly for Edwards, the Iowa terrain was far better for them than the New Hampshire terrain. So while Hillary could sit pretty and wait for Edwards in New Hampshire, Edwards would have to beat Tom Vilsack in Iowa to have any traction.
    This plan was not to be for two major reasons. The first is that because of Obama's strengths, both among African American's, who while it is now tied, it would have been nearly impossible for any other candidate to get to that tie, and his quickly demonstrated fundraising prowess.  It was too risky to allow Obama a win in Iowa.  Secondly Tom Vilsack was not able to garner the type of Iowa support that would be needed to allow Hillary to stay out of Iowa, for anything other than political calculation. Many people on her staff argued for this approach but ultimately the weakness of Vilsack and the strength of Obama required that she engage in Iowa.  Vilsack joined the team quickly, hoping that winning Iowa for Hillary would grant him the Vice-Presidency. The Clinton Campaign wanted out of Iowa but were forced to play there by the strength of the Obama threat and the lack of strength of Tom Vilsack in Iowa.

A wrinkle in Iowa
    This race is now very much engaged in Iowa and if for all purpose a tie, however there is still a wrinkle in this tie, in the person of John Edwards. It should be very clear that at this point John Edwards is training in the neighborhood of 80% of his fire at Hillary and this may be a tip off to something that could change the race.
This is because those familiar with the Iowa Caucus rules know that a candidate needs 15% support in every caucus to get any votes in the caucus. This rule led in 2004 to the Kucinich and Edwards deal, which was a promise that wherever the other candidate was not viable their supporters would Caucus for the other.  The margin if it stays in the same neighborhood as it is now could mean that whoever cuts the best "deal" would end up winning, an Edwards-Obama deal would at this point very likely beat Clinton and who ever their campaign struck a deal with. In short since Edwards is trending, however slightly down, this could mean an Obama victory in Iowa, which clearly sets up the rest of the scenario

Prediction, Obama 33% Clinton 30% Edwards 22% Richardson 7% Biden 4% Dodd 2% Kucinich 2%

On to New Hampshire
    Assuming Obama is able to win in Iowa, New Hampshire becomes a very likely target for a next victory. It is here where history should be as great a cue as polling. The current polling is bad,  but it is also does mirror the trends of nationally. When the race is not engaged on T.V. and when it is quiet. Senator Clinton does better, when the race is engaged, like Iowa, The Clinton Campaign does worse.  All of the current polling in New Hampshire has been conducted, while  Clinton   was on T.V. and Obama was not on T.V.  This important difference makes  this  Obama's low point in the state of New Hampshire . Senator Clinton is at roughly 40 and Senator Obama is at roughly 20.  However once the race is engaged, it is entirely likely the margin will shrink to ten with Obama gaining support to around 30, while Clinton will remain at roughly 40%. Assuming an Obama-Clinton-Edwards finish in Iowa, the odds are very good that, the rest of the field combined will be held to around 20% or less. History has shown that with the exception of Massachusetts's candidates, New Hampshire Democrats are likely to give a boast to the Anti-Establishment candidate over the Establishment Candidate. For example Bill Bradley almost won the New Hampshire primary.  This despite the fact hew was being far more badly beaten in National Polls and Establishment support than Clinton is beating Obama now.  Look for the gap to narrow to around ten points by Iowa and be erased after an Obama victory in Iowa. Obama will win New Hampshire

Prediction
Obama 42% Clinton 38% Edwards 10% Richardson 5%, Dodd 2% Biden 2% Kucinich 1%  

South Carolina and Nevada
    At this point it is a two-person since those Candidates remaining, if any,  are not likely to reach the 15% of the vote necessary to qualify for delegates

    South Carolina is already showing the signs of being an engaged state over a non engaged state, while the most recent poll has a nine point Clinton lead this is much smaller than her leads nationally and is therefore is very hopeful sign. After two wins by Obama in New Hampshire and Iowa and based on this most recent polling, it is very likely that Senator Obama would be able to win South Carolina.  
    Prediction Obama 55% Clinton 45%

    Nevada
    This state is probably the hardest to get a read on because there is simply no history. On the hand Senator Clinton is completely and totally owning amongst electeds in the State, on the other hand it is a Caucus that in general will benefit Senator Obama. Senator Clinton's poll leads are also sizable.  I would give the edge to Senator Clinton but by a small margin
Clinton 53% Obama 47%

National/Feb 5th.
     Could a Clinton lead of 20 points nationally hold up against losing three out of four first contests? Yes, but is it likely too, probably not.  Clinton fans at this point are probably screaming, but what about Michigan and Florida, the bottom-line in those two states, where Senator Clinton will win Florida and probably Michigan, they award no delegates in either contests, so while those delegates will probably be seated at the DNC it would probably be by the nominee.
    Feb 5th has at this point, 19 states scheduled and it is clearly important to remember that Democrats allocate convention delegates proportionally based on the results not winner take all.  This makes a huge difference when reading polling, in lets say New Jersey the polling shows Senator Clinton leading Obama by a 49-23 margin, this may not actually be at this point all the crippling because simply put the Obama goal in New Jersey is not victory but instead 40 to 45 percent of the delegates. If the results were to happen as I suggested, the odds are quite likely that the question would soon become a battle for Delegates.
A quick at the 19 states shows some clear advantages for one candidate or the other in many of the Feb 5th states.  

The states currently scheduled for Feb 5th are
Alabama
Alaska Caucus  
Arizona
Arkansas
California
Colorado Caucus  
Connecticut
Delaware
Georgia
Illinois
Minnesota Caucus
Missouri
New Mexico Caucus
New Jersey
New York
North Dakota
Oklahoma
Tennessee
Utah  

While not an exact science I believe the states would break as follows.

Obama: Alabama, Alaska, Colorado Connecticut Delaware Georgia Illinois Minnesota North Dakota Utah
 Clinton:  Arkansas New Jersey New York
Swing:  Arizona California Missouri New Mexico Oklahoma Tennessee

A clean sweep by either candidate of all six-swing states Feb 5th would probably net them the nomination. However any other split and I believe the race would press on.

Virginia as high noon [Other February contests]
    This is where I believe Senator Obama will clinch the contest and hence the nomination.   The next two contests are over the following Weekend of Feb 5th Louisiana on Saturday the 9th and a Maine Caucus on the 10th.  Both of these contests favor Senator Obama.  After a Southern sweep with the exception of Arkansas [I believe Obama will win Oklahoma Tennessee and Missouri, drop Arizona and California by small margins and have no way to predict a New Mexico Caucus] I believe Senator Obama will Louisiana. A Maine Caucus also clearly favors Senator Obama. This leads into Feb 12th with Senator Clinton in desperate need of a win and two states confronting her, Maryland and Virginia. Based on a reading of the Cardin-Infume Maryland Senate Primary, there is simply no way Clinton can defeat Obama there.  It would then rest entirely on Virginia.  Senator Obama based on his endorsement from popular Democratic Governor Tim Kaine could be seen at this point as a slight favorite but it would be a very closely fought contest and one which would decided if Senator Clinton would be able to continue. The last three contests in February all favor Senator Obama [Washington Wisconsin, Hawaii] So while the next real delegate number  [Texas Ohio Massachusetts and Vermont] would seem appealing, it would be hard for Senator Clinton to continue if she were forced to endure a whole month from Feb 5th to March 4th without a win.      However a win in Virginia would more likely than not send this race to a deadlocked convention, in which super delegates who so far overwhelming favor Senator Clinton would play a powerful role.

Conclusion
    An Obama win in Iowa would likely set up Obama wins in New Hampshire and South Carolina. Which would force the race into a tie but one in which the first round of states actually favor Senator Obama. Florida did Senator Clinton a huge disservice to Senator Clinton by disenfranchising itself as it would be one of her top five states nationally and also the second largest delegate state for her strength.  This race is anything but over. Senator Obama has a very real path to the nomination.