It is one of reason endorsements can actually matter. Republicans tend to be a lot better about being team players, as well as more inclined to vote for SOMEONE out of civic duty. I know many liberals who refuse to vote because they consider no candidate deserving, and have a good friend who long insisted voting makes one culpable for all government failures and wrongdoing.

My own impression is that, historically, Republicans tend to suffer far less than Democrats from divisive primaries, with the notable exception of when TR ran for a third term as an independent, spawning the Progressive Party in the process. You guys do not have to deal with herding cats or holding a big tent together; the only real concern is that Libertarians might say, "a pox on both their houses," but that is always a concern. With Dems it seems the whole party is like that, refusing to vote for anyone who does not cater to their own personal interest, or "stole" the nomination from their personal hero.

That is also the biggest threat to Obamas re-election: Not that people who voted for him last time will vote for Romney, but that they will stay home while the far more energized GOP anti-Obama base rushes to the polls to defeat him. As a general rule, I think any Democrat needs a lead of a few extra points simply because their turnout less reliable than the GOPs.