First, the states to watch are rather easy to see:
They all had small margins (under 7%) - whether for McCain or Obama. All except Montana are relatively large states with 11 or more electoral votes. Their total electoral votes were 115 (while the 2010 census moved some votes around, these states still total 115). However, even if the GOP wins all of them, if the other states remain static, Obama still wins. It's not enough for the GOP to pick off the easy targets, they have to also do the harder ones.
For McCain to have won the election, he would have needed to win all of those states, PLUS another 4
electoral votes (given the census changes). The next easiest states for the GOP to take are Colorado, Iowa and New Hampshire, all of which had a margin of 9% for Obama. Nine percent is a big wall to climb. Some people think Minnesota (10% margin) and Pennsylvania (11% margin) and even Nevada (12% margin) are also in play. But keep in mind that McCain only won Texas by 12%. No one seriously thinks Texas is going Democrat again - despite the larger Hispanic and urban growths in Texas that tend to vote Democrat. Pennsylvania has voted democratic in the last 5 presidential elections. I think Minnesota, and Nevada are becoming Democratic strong holds. Minnesota is part of the expanding North East/Great Lakes Democratic stronghold and Nevada has a growing Hispanic population.
Worse, the GOP is going to have to fight to keep Missouri, Montana, and even Georgia. Georgia is over 30% black, which makes for a big base, and gained an electoral college -in part because the black population increased more than the white population (2000 census said 28.7% 2010 said 30.5%). In fact, even Arizona may be a tough state for the GOP to keep - McCain won it with only a 9% margin and it was his home state.
Note, this does not take the 2010 mid term elections into account. All those states I said they needed to win for the presidential election? The GOP pretty much won them in the 2010 midterms. But that is fairly typical - the losing party in the presidential election tends to recover in the midterms, but they also generally lose it all back in the next presidential election. Also, see my previous post - the 2010 midterms did not have Obama running for election. It was the ultimate 'early poll' running an unnamed candidate against Obama. That meant all the angry conservatives showed up to vote, while the happy democrats staid home (to their later disappointment). Anyone looking at Wisconsin knows that not all the GOP gains in 2010 are going to translate into wins in 2012. There are even recall elections in some cases. The 2008 election was a named candidate vs Obama, which makes it more accurate than un-named vs Obama.
Part of the problem for the GOP is that Obama took most of the larger electoral states. McCain won just as many small states and 2 more medium states, but Obama won 13 out of 17 Large states, while McCain only won 4. Larger states may have smaller margins, but those margins represent more people, and more people = more money spent on electioneering.
Also note that in the states Obama won, he averaged a 19.1% margin, where as McCain only had a 16.% margin. Part of this may just be that McCain was not conservative enough for the conservative voters. But the fact that he lost the general election meant he was not liberal enough for the moderates. The more he shored up his base, the more he lost the independents, and vice-versa. Whoever goes up against Obama will probably have the same problem.
Obama on the other hand has a rock solid hold on the liberal base, because of race and the constant GOP harping on "socialism". Despite Republican pipe-dreams, they can not attract the black vote. Worse, every time the GOP makes ridiculous, propaganda statements about socialism, they increase their base support, but lose independents while Obama also increases his base support. So Obama has the luxury of focusing his appeal on the independents and let Republican fear-mongering maintain Obama's own base. He can sound reasonable, while letting the GOP sound extremist. Note this is extremely important in a national election, but not as important for the state and local elections from the midterms. The nation has a real center, while states are often fairly partisan. Things you say in one state anger people in other states. It is easier to win a state election because they tend to be more uniform in their ideology. That is why the Democrats are unlikely to win Idaho, and the GOP won't win Hawaii. The country as a whole however has a wider range.
Of course it also helps that Obama, unlike the current crop of GOP candidates actually IS a moderate that appeals to independents.
The GOP has a lot of work cut out for them. I don't think they can do it - not unless Obama makes some serious mistakes. Even if the economy gets seriously worse, it is hard to convince voters that the GOP can fix the problem they so clearly are being blamed for (Hint, Reagan paid for his tax cuts with lowered defense spending. If you want to start a war, you can't also cut taxes.) Independents don't blame
Here are the 2008 election results I used for my analysis.