I think Republican unity problems of late have been extremely overblown.
There's no doubt NY-23 was a big old mess, and if that's replicated on a broader scale next year the GOP will have some problems. But I think that whole charade was a once in a lifetime thing.
New Jersey and Virginia provide us with some better clues as to the state of the party.
In New Jersey we found Chris Christie winning 82% of the Republican vote to Jon Corzine's 72% of the Democratic vote. And in Virginia we found Bob McDonnell getting 94% of the GOP vote to Creigh Deeds' 87% of the Democratic vote.
Contrast that to last year. Our final Virginia poll had Barack Obama getting 89% of the Democratic vote to John McCain's 87% of the Republican vote. And the New Jersey exit poll showed Obama getting 89% of the Democratic vote to McCain's 85% of the GOP vote.
In both cases the Democrats were more unified in 2008 but the Republicans were more together in 2009. And at this point I expect that to continue in 2010. GOP voters know they have to support their party's nominee- as chosen in the primary- if they're going to start on the path back to power in Washington DC.
The problem in NY-23 was that the party rank and file didn't get to make that choice and it caused a huge splinter and lots of resentment...but that won't be a concern in many races next year. There will likely be some spirited primaries but by and large the party's voters will get on board in the general election to fight off the greater evil.
I think ultimately Democrats are going to have a harder time keeping their voters on the same page in the general election next year than the Republicans.