Morris is really the only place the Republicans have a strong handle on and that's not much in the full picture of North Jersey. I also completely disagree about Somerset, I can't see it in the Republican column nationally barring a Romney win. It has gone from 16.5% more Republican than the nation in 1992 to now only 1% more Republican, with consistent movement in every election between. Everywhere in the county has been lazily moving towards the Democrats for decades now. In order for Republicans to actually stake a claim to the North Jersey suburbs, we'd have to see a massive shift back in the inner suburbs. They've got a weak handle on the outer ones, but no presence in the inner ones. In 2009, almost all of North Jersey trended Democratic compared to the state as a whole, particularly Bergen. The shore and South are what carried Christie. That's not a good sign for Republicans in suburban North Jersey. Bergen and Somerset are perfect examples of an increasingly uninterested suburban New Jersey towards Republicans. If Romney can snap those areas back that he has performed well in while capitalizing on the moves Middlesex/Monmouth are making towards Republicans, then he'll look good. Other than that, there isn't much Republicans can do to get Jersey.
A lot of that switch in places like Somerset you are talking about occurred from 1990 to 2000, not 2000-2010. This decade, most of the suburban counties have stayed where they are, or headed right, relative to the nation. The state as a whole has a decreasing PVI since Gore got 56% here.
Monmouth (part of which is clearly in the NY metro, which is how I define North Jersey) went from 50% Gore to 45% Kerry to 47% Obama to 31% Corzine in 2009. A clear shift towards Republicans.
Middlesex went from 60% Gore to 56% Kerry to 60% Obama to 45% Corzine. Not particularly trending either way. It's astonishing that Christie won here.
Morris went from 43% Gore to 42% Kerry to 45% Obama to 31% Corzine.
Bergen went from 55% Gore to 52% Kerry to 54% Obama to 49% Corzine. Not too many swing voters here, which makes sense given the geography of the county. The GOP strongly controls the northern section.
Union went from 60% Gore to 59% Kerry to 64% Obama to 51% Corzine. Obvious problem here.
Sussex, Warren, and Hunterdon have also moved right. Makes sense as these areas are dominated by whites and of course Christie was putting up 65-25 victories here. So I don't think your last statement is really quite accurate; Christie was carried by Monmouth, Ocean, and the cluster of Northwest counties, all of which we have a full grip on. These areas are Republican across the board as we hold all the legislative seats there.
Comparison of presidential election results to gubernatorial elections = apples to oranges. Doubly so with someone as individually unpopular as Corzine. Wait for 2012 pres results and we'll talk.
Democrats reliably win statewide elections in West Virginia yet have recently voted for the Republican nominee for President by big margins in the last three Presidential elections. I figure that it could go easily for a Southern moderate Democrat (Carter -- twice!, Clinton) but not for a d@mnyankee Democrat since HHH in 1968. Culture matters greatly in deciding what candidate can win what state -- and Barack Obama is a horrible match for West Virginia. The only way in which President Obama wins West Virginia in 2012 is if the Republicans nominate a weak or extremist candidate.
Quality of a candidate matters greatly, too. A very effective Governor or Senator might successfully navigate against a landslide against his Party. Some can govern or legislate effectively while in the minority; some can't.
