Republicans main problem was they were taking a hard line on too many issues and alienating the average voter in the process. The average voter only feels strongly about a few issues. The Republican Party in not so many words was telling people to agree with them on every issue or that they were wrong and not welcome in the Republican Party.
I'll break down the issues they were alienating people on with the individual social groups.
The average voter -
Healthcare reform - the average voter is very responsive to reforming our healthcare system. McCain actually had a decent plan, but he essentially handed the healthcare issue to Obama on a silver platter. Republicans just conceded from the start on this issue. They didn't try to even offer much of a solution.
Environment - the average voter is concerned about environmental issues to at least some degree. This was another issue that Republicans handed to Democrats on a silver platter. Same as above. Did not even try to offer a solution.
Women -
Abortion - women are more likely on average to be pro-choice. Democrats are at least willing to compromise on abortion to some degree. The Republican Party platform was you are either with us or against us.
Hispanics -
Immigration - Hispanics went 2-1 for Obama (66-33% or so). Republicans are sacrificing the fasting growing demographic in the country with their stance on immigration.
Blacks -
Went 95-5% for Obama. Need I say more? The most the Republican Party has done to try and incorporate blacks into their party is to put a black person in every photo op they have and install Michael Steele as a figurehead of the RNC.
Post-Graduate/Professional Degree Holders -
Science/Environment/Religion/Morality - This is also one of the fastest growing demographics in the country. We are an increasingly educated society, at least in terms of the degrees we carry. And the Republican Party's anti-science and staunchly pro-religion standpoint turned off a lot of people. The same thing with their stance on sex education and all other kinds of "moral" issues
Young People (younger than 30) -
Just about every issue - Republican performance with the young was pathetic to say the least. Republicans are risking losing an entire generation to the Democrats. People tend to solidify their party identification relatively early in life.
The only demographic that Republicans did particularly well with was white males. Coincidentally, white males are one of the fastest SHRINKING demographics in the country.
I still think the Republicans have a very bleak future ahead unless they update their party platform significantly. They are stuck in the 20th century while the Democrats are moving aggressively forward on a lot of issues.
We had two bags of grass, seventy-five pellets of mescaline, five sheets of high-powered blotter acid, a salt shaker half full of cocaine, a whole galaxy of multi-colored uppers, downers, screamers, laughers…Also a quart of tequila, a quart of rum, a case of beer, a pint of raw ether and two dozen amyls. The only thing that really worried me was the ether. There is nothing in the world more helpless and irresponsible and depraved than a man in the depths of an ether binge. –Raoul Duke
It is hard to shed anything but crocodile tears over White House speechwriter Patrick Buchanan's tragic analysis of the Nixon debacle. "It's like Sisyphus," he said. "We rolled the rock all the way up the mountain...and it rolled right back down on us...." Neither Sisyphus nor the commander of the Light Brigade nor Pat Buchanan had the time or any real inclination to question what they were doing...a martyr, to the bitter end, to a "flawed" cause and a narrow, atavistic concept of conservative politics that has done more damage to itself and the country in less than six years than its liberal enemies could have done in two or three decades. -Hunter S. Thompson