Professor Balkin has a must read post on the break-up of the Reagan coalition and how it was created by the failures of the Bush Administration. He also argues that the rise of Obama is a direct off-shoot of this collapse; Obama's rise is thus directly attributable to the deep failures of the Bush Administration.
If 2008 turns out to be a pivotal election, defining a new political era, it is important to give credit where credit is due. Two key reasons for the change will be the crackup of the coalition of the dominant party of the era, the Republicans, and the almost complete political failure of George W. Bush and his chief political adviser, Karl Rove.
Professor Balkin's point is something that I've been saying here for a while: the elements of the Reagan coalition no longer have anything in common such that they can remain together under one umbrella. Where Professor Balkin goes further- correctly - is in placing the blame for this at the feet of Bush's failed policies.
Each group within the GOP coalition obviously has its priority issues. The coalition has held together by allowing each group to get its way on its priority items, while subsuming their secondary and tertiary priorities to the other groups who placed a higher priority on those issues. But the failed policies of the Bush Administration have forced a reshuffling of each group's priorities.
For example, social issues have long been the top priority for evangelicals; but the failures in Iraq and on economic issues have made those issues as or more important to evangelicals than they once were- hence you have the rise of Mike Huckabee's populism.
For libertarians, economic issues were historically the top priority. But the failures of the Bush Administration on civil liberties, Iraq, and the GWOT, amongst other things, have led to foreign policy and civil liberties becoming as or more important to libertarians. Hence, the rise of Ron Paul and the massive shift of the libertarian vote to the Democrats in 2006.
Similarly, economic issues were historically a top priority for those more broadly defined as fiscal conservatives/social liberals. Again, Iraq and the GWOT, along with Bush's relatively extremist social policies have driven this group either out of the GOP coalition or to candidates like Giuliani and McCain.
...And so on. The only group(s) that still seem to hold on to the idea that everything is just fine with the Reagan coalition are the Romney supporters and, to a lesser extent, the Thompson supporters (who tend to see where Bush has failed miserably and that he is Reagan's antithesis, but still hope that the coalition can be reunited).
The result of this is that the GOP will likely need to be re-built in the coming years along new ideological lines; there is even a chance that the party will simply split into two (though Obama's rise may prevent that by co-opting many of those who would have tried to create a new party).
As Professor Balkin concludes:
[I]f Ronald Reagan was the Great Communicator, George W. Bush is the Great Destroyer of Coalitions.