If your candidate lost yesterday, I'm sorry. If you lament because you assumed that your candidate would have implemented superior public policies, then you can feel better already because your sorrow is based on a false assumption.
Democrats and Republicans clearly have different rhetoric. But rhetoric is not policy. Republicans talk a great game when it comes to cutting government spending, but President Clinton's administration had one of the lowest ratios of government spending to GDP. President Bush added immensely to Medicare spending with the Prescription Drug Act. Democrats talk a great game about helping the poor, but they pushed through a bill to tax America in order to bail out Wall Street. FDR started Social Security, but Nixon did the most to increase its spending. Democrats talk about limiting the power of the state when in comes to the death penalty, but a Republican Governor (Ryan in IL) put a moratorium on the death penalty.
Do you remember when Democrats were devasted because Roe-v-Wade would be overturned once President Reagan made his Supreme Court appointments? Well, those appointments happened and Roe-v-Wade still stands. I could go on and on with examples.
Economic theory suggests that political party might not affect policy, but instead merely reflect public policy preferences of the citizens. With some exceptions (see below), political parties compete with each other. Obama was one of the most liberal U.S. Senators because he faced little contest in Illinois, but became quite middle-of-the-road when it came to the Presidential race. Politicians are politicians first and (at best) ideologues second. A public opinion shift may give one party or another a small advantage and thus create a correlation between public policy and party-in-power, but this does not mean that political party itself has a significant impact on policy. Indeed, it would be inefficient if it did.
A number of economic studies have failed to find a correlation between party-in-power and public policy. Others have found a correlation (Professors Besley and Case have a nice survey in the JEL), but even there the implied impact is quite small. For example, Besley and Case look at state governments (where spending is about 1000 1982-dollars per capita per year) and find that governor's party is not correlated with spending and that a 10 percentage point increase in the Democratic party's share of the state legislature is associated with additional state government spending in the amount of $10 per capita per year. $10 per capita per year could be less than the cost of voting itself! Furthermore, effects at the state level may be larger than they would be at the national level because state-legislature elections are often uncontested and the whole economic logic cited above presumes competition.
Professors Snowberg, Wolfers, and Zitzewitz tried to look at situations in which party-in-power was significantly different even when citizen preferences were not. They found some effects, but they were also quite small. Eg., a Bush administration (rather than Kerry or Gore) was expected to increase stock prices by 2-3%. That is pretty trivial, given that the stock market fluctuated that much in the 20 minutes it took me to type this entry (back in October 2008).