The Presidential sample stands out for its extremely small movement from final polls until election night. Even though undecideds break overwhelmingly--better than 6 to 1--in favor of the challenger in a Presidential race, pollsters seem particularly adept at national trial heats in Presidential races. Probably because of the extreme amount of national attention given to the Presidential race, far more people have made up their minds going into the booth than in other elections. While we should not expect significant movement from the final polls on November 1 to the final results on November 2, whatever small movement there is will be almost entirely for Kerry.

Update: TruthIsAll took a moment out from weathering Hurricane Frances to drop me an e-mail:

I allocate undecideds to Kerry in five simulation cases of 50,55,60,67,75%, adding the allocation to all current state polls downloaded from electoral-vote.com into my Excel spreadsheet.

This way we can see the effects of these assumptions on Kerry's average EV and win probability for each case. The summary is on the first screen [of his website] with detailed graphics and analysis following.

Kerry has a better than 98% chance of winning if he gets 75% of the undecided:

STATE POLL MODEL   

Monte Carlo Simulation (5000 trials)  

          

Undecided allocation    

KERRY:       50%   55%   60%   67%   75% 

Trial Wins  2755  3330  4014  4825  4934 

          

Pop. Vote % 49.97 50.21 50.61 51.41 51.81 

Win Prob %  55.10 66.60 80.28 96.50 98.68 

          

ELECTORAL VOTES     

Average      273   280   290   311   322 

Median       273   279   289   310   322 

Maximum      353   366   376   386   391 

Minimum      171   178   193   242   240 

          

States won    24    24    25    27    27 

          

NATIONAL MODEL %     

Pop. Vote   50.47 50.84 51.21 51.59 51.96 

Win Prob    60.79 68.90 76.18 82.41 87.50

If I'm reading this correctly, even if Kerry only gets 50% of the undecideds, according to TruthIsAll's model Kerry has still got a 55% chance of winning, although as a minority president (less than 50% of the popular vote), and carrying only just enough states to win (273 electoral votes). If Kerry gets the high end of the 66-34 split Chris refers to above, then Kerry's chances of winning (according to TruthIsAll) is 96.5%, with a majority (51.41%) of the popular vote and a good margin in the Electoral College.

BTW, I should note that in a comment on MyDD, Chris Bowers makes clear that the data he was working with was solely for the undecided split from the very last poll taken before election day, and his conclusions are not necessarily applicable to polls taken earlier. Also, Gerry Daly, proprietor of Dales' Electoral College Breakdown had some comments critiquing Chris' analysis which are worth looking at.