2008 Primaries: All states vote on the same day

[Mr. Morden]

Clinton would have won the Democratic side, or at least gotten a plurality of the pledged delegates.

On the GOP side, McCain probably wouldn't have even been in the race by primary day.  He was completely broke by Summer 2007.  His only hope was to throw everything into NH, and hope that a win there would give him momentum going into the following states.  If all the primaries were on the same day, that wouldn't have been an option, so he could very well have dropped out.  (OTOH, he might have stuck it out just so he could get a handful of delegates, and use them to bargain at a brokered convention.)

I presume that Giuliani would have ended up with a plurality of delegates.  Much of his collapse seems to have coincided with all the negative media attention about how badly he was doing in the early states.  If there *were* no early states, that wouldn't have happened.  But the other open question is how much $ Romney would have given his campaign to run ads nationwide.  Possibly a lot more than Giuliani could raise.

[Mr. Morden]

Be careful, Mac was back just after Christmas holidays, probably because of international news (Benazir Bhutto's assassination, e.g.).

I honestly think a good deal of McCain's national surge was due to the positive media coverage he was getting from his seemingly miraculous campaign turnaround in NH.  If doing a hundred town hall meetings in NH hadn't been a viable strategy, he wouldn't have been able to pull that off.

The other part of the equation re: McCain's rise was Giuliani's fall, and Giuliani voters shifting to McCain.  It's hard to assess how much of that would have still happened if we had a single national primary day.  I'm not sure how much of Giuliani's collapse would have happened with a national primary day.  Could he have coasted through to election day without too many voters ever really figuring out how out of step he was with them on social issues?  I think maybe he actually could have.

In a nationwide primary, the electoral battlefield is just so enormous.  No state would get nearly as much attention as Iowa and NH do IRL, and so the average voter wouldn't be nearly as well informed about the candidates as the voters are in the early primary states IRL.  This would have enormous implications for how the campaigns are run.  Of course, the implications are probably too complex for any of us to figure out....