OK good, now that the discussion has started, I'll weigh in.
In my opinion, Republican victories have been because of a two prong strategy to build up a solid base of support from which to campaign. The first and more powerful (lately) of these is a courtship of religious voters by backing religious values. This has worked better than I think even the Republicans have hoped, because they've been able to move enough towards moderate religious views to get a larger percentage of religious voters while not losing the support at the polls of the fundamentalists and evangelicals.
The second strategy has been based around "fiscal conservatism" which at its face appears to be a rational claim for smaller government and less government intervention (such as bailouts, social security, medicare, etc). However if you trace the movement back to the early 2000's it is actually the result of the Libertarian party being more or less consumed by the Republicans. This strategy has proved extremely effective, in that Libertarians have always had well constructed ideas and been highly competent in projecting those ideas.
The combination of these two strategies, has been extremely effective, in that the appeal to religious voters has allowed for the Republican party to keep up their base numbers, as well as sweep Midwest and Plains States, while the use of libertarian ideas, arguments, and candidates has lended the republicans ideological legitimacy and the appearance of a strong intellectual base.
However I think that this strategy is also ultimately failing them. The change of the American public's opinion on issues such as gay marriage indicate that the classically conservative religious base is eroding. Evangelical leaders, who represent one of the most energetic and motivated of the Republican constituencies, have been noting for years that the rising generation of evangelicals are far more socially liberal than the previous generations. Many are unopposed to gay marriage, some even support it; a growing number see the value and need for the large welfare programs the U.S. employs; and some are even switching sides all together. This demographic change in the religious base is going to leave the republicans representing an outdated and backward minority, who no longer have the clout or energy to sweep elections for them. (Obviously this kind of change will take several election cycles to become evident)
Regarding the "Fiscal Conservative" movement, many of these ideas, would be extremely unpopular to the majority of Americans, cuts to social security are likely to never be passed, or if they do get passed it will be an electoral nightmare for the party that passes them. The austerity response that fiscal conservatives would have had us employ in response to the recession has shown just how effective it can be in the Euro Zone. While the libertarian ideology has lent intellectual credibility to the party thus far, as the actual effects of such policies become more widely known (an effect that requires at least several years more likely 2 or more election cycles), the legitimacy offered will no longer be there. The republicans would be better served to move to a new ideology before their current one becomes discredited.