I've spent a few hours going through the delegate allocation rules for each state posted on National Journal's site. There are about as many variations in delegate selection rules as there are states voting on Tuesday (that is a slight exaggeration, of course) which makes it nearly impossible to come up with any reasonable way of figuring out how many delegates each candidate will win on Tuesday. But I'll take a shot at a prediction anyway...
Let's start with the states with the most simple allocation plans. AZ, CT, DE, MO, NJ, NY, and UT each give all of their delegates to the winner of the statewide vote. McCain seems to have a safe lead in AZ, CT, NJ and NY, which would give him 230 delegates (50 from AZ, 27 from CT, 52 from NJ, and 101 from NY). UT is safely in the Romney column, which will give him 36 delegates. That leaves two winner-take-all states. In DE (18 delegates), the only poll taken recently indicates a 41% to 35% lead for McCain over Romney. In MO, the polls seem to indicate that either McCain, Huckabee, or Romney could win the state's 58 delegates, but McCain has a small lead in the pollster.com average, so let's give those to him.
MA allocates its 40 delegates proportionally according to the statewide vote. Based on current polls, Romney would receive about 25 of those delegates and McCain would receive 15.
TN allocates its delegates proportionally statewide and by congressional district unless someone receives 2/3 of the vote. Right now, polls put McCain at about 32%, Huckabee at about 25%, and Romney at about 22%. The number for Romney is significant since the threshold for qualifying for delegates is 20%. If we assume all three qualify and get a share of the vote proportional to what the polls show, then McCain would receive 21 delegates, Huckabee 16, and Romney 15.
Ok, so that was the relatively simple part, now come the complicated states. First, we have no polling for AK, AR, MT, ND, and WV (which is a convention), so we don't know who will win those 123 delegates. Second, CO, MN, and IL all appear to have events that don't really lead to any pledged delegates being selected, so I won't make any guesses to how that will turn out. That leaves us with AL, CA, GA, and OK. Each of these states allocates part of their delegates to the winner of the statewide vote, and the rest according to who wins the vote in each congressional district. But this mix varies significantly from state to state. While AL, GA, and OK, all award about half of their delegates to the winner of the state, CA only awards 11 delegates to the state winner and the rest are allocated by district. Since we don't have congressional district level polling, the estimates we create for these states are going to be even more subject to error. But I'll give it a try:
AL gives 24 delegates to the winner of the state and the remaining 21 go to winners of each congressional district. The polling shows McCain and Huckabee essentially tied (37%-35%) with Romney farther back (19%). If McCain wins, that gives him 24 delegates. Then let's assume that McCain wins 4 of the congressional districts and Huckabee wins three. That gives McCain another 12 delegates and Huckabee 9. The total then would be: McCain 36, Huckabee 9, Romney 0.
The polling in GA (30 statewide, 39 among districts) shows a three way split: McCain 32%, Romney 29%, and Huckabee 27%. Let's assume McCain wins the state and 5 of the congressional districts, with Romney and Huckabee each winning 4 congressional districts. The total would then be: McCain 45 delegates, Romney and Huckabee with 12 each.
The polling in OK (23 statewide, 15 among districts) shows McCain with 40%, Huckabee with 28%, and Romney with 21%. Given the way OK's districts are divided, I'd say that McCain would win the state and 3 districts, while Huckabee might pick up 2 districts. The total would then be: McCain 32, Huckabee 6, Romney 0.
Finally comes CA (11 statewide, 159 among districts) where polling shows a tight two-way race between McCain and Romney. Let's assume that McCain wins the state and one more district than Romney. That would give McCain 92 delegates and Romney 67.
So, before I add this all up, keep in mind that this estimate is likely to be much farther off than the Democratic estimate I calculated, largely because of how many of these delegates are distributed by winner-take-all rules at the congressional district level. But here is the very rough estimate of how things might turn out on the Republican side:
McCain would win 547 delegates, Romney would win 155, and Huckabee would capture 43 delegates, with another 261 delegates being determined in states where there is no polling or where the process should keep us from having a clear idea of how the delegate count might turn out. Even without the 261 delegates that we aren't sure about, that would get McCain about halfway to what he needs. Would that be enough to force Romney and Huckabee from the race?