We have arrived at the biggest day in the history of primaries.  Almost half of these United States are conducting their primaries or caucuses today.  Over 1000 delegates are at stake on the Republican side and twice that are being contested on the Democratic side.  Truly this is the big one.

Here's how I see the Republican races unfolding today.  John McCain will be the big winner.  He is still riding the momentum from his victories in South Carolina and Florida - plus he enjoys a structural advantage.  Unlike the Democrats, who award all delegates (except super delegates) proportionally according to the vote, state GOP conventions have several methods for allocating their delegates.  Many states have a winner-take-all format.  Others use a proportional model.  Still others choose a modified winner-take-all system which takes congressional district results into account.

It just so happens that in many states where McCain is ahead, the method is winner-take-all.  As a result, he stands to gain large delegate blocks in such states as New York, Arizona, Missouri, and New Jersey.  On the other hand, with the exception of Utah, states Mitt Romney might be expected to win break down the allocation of delegates to more than one candidate.  For example, Romney's home state of Massachusetts employs a proportional model.

The bottom line is that McCain's delegates will come easier than Romney's, increasing the effect of his strong polling numbers nationwide.  I'm predicting McCain will win 60% to 65% of the delegates at stake today.  Mitt Romney will come in with 25% to 30% or so, and Mike Huckabee, around 10%.  Ron Paul's best chance of picking up delegates will come in Alaska.  Other than that, he may snatch a delegate here and there, but his haul won't amount to much.

On the Democratic side, the fact that every state awards proportionally will make it difficult for either Obama or Hillary to gain an overwhelming delegate advantage.  In fact, I don't see either candidate earning more than 55% of the delegates to be awarded today.  Looking at the polling data, I would say Obama will get 25 to 75 more delegates than Hillary.  Last month, conventional wisdom pointed to a Republican brokered convention.  After today, ironically, it may be the Democrats who will be more likely facing a convention fight.

Here is a roundup of other blogger predictions, followed by two tables containing mine.

NB Politico  Tsunami predictions galore! Texas Gringo at RedState  Extensive breakdown of the GOP races. The Square Deal  Romney's California surge may give him a reprieve. Coldheartedtruth  C.H. Truth says Obama could pull this off. Freedom's Lighthouse  McCain is sitting pretty. Outside The Beltway  It won't be over tonight - at least mathematically. Church and State  Huckabee to outperform in the south. Sister Toldjah  Hillary takes Massachusetts from Obama/Kennedy. Confederate Yankee  Results: DEM - advantage Obama, GOP - advantage Obama. Allah Pundit at Hot Air  Hillary and Romney win California. The Political Tipster  So many polls, so little time. Label Free Zone  Neal Ford see a very big night for McCain and Obama.

If you have posted predictions, send me an email so I can put you on this list.