Romney's flip-flopping was only one reason for his loss. Obama's ground game played a much bigger role, IMO. Rather than trying to woo mercurial independents, Obama simply used the changing demographics to his advantage to turn out a lot of new voters who simply hadn't voted in previous elections. Romney's ground game was much weaker because Obama had been developing his over the last 4 years and didn't have to waste time and money on a long primary campaign.
In swing states like FA and CO, he got many US-born Hispanics who hadn't previously voted (many of whom recently became adults) registered and got them to vote for him by telling them that Romney would deport their foreign-born family members who are in the country illegally. As explained by the NYT[0]:
> In Chicago, the campaign recruited a team of behavioral scientists to build an extraordinarily sophisticated database packed with names of millions of undecided voters and potential supporters. The ever-expanding list let the campaign find and register new voters who fit the demographic pattern of Obama backers and methodically track their views through thousands of telephone calls every night.
> That allowed the Obama campaign not only to alter the very nature of the electorate, making it younger and less white, but also to create a portrait of shifting voter allegiances. The power of this operation stunned Mr. Romney’s aides on election night, as they saw voters they never even knew existed turn out in places like Osceola County, Fla.
In Ohio and Pennsylvania, Obama partially relied on the black vote. These are people who are guaranteed to vote for him, so the main issue was getting them to vote in the first place. He set up neighborhood election stations in black community gathering places like barbershops and beauty salons, getting people to register their friends and family and encourage them to go to the polling stations on the day of the election. In fact, the voting rate among blacks was higher than among whites in Ohio - an amazing coup.
Another key constituency in Ohio and PA was the auto workers and other blue collar voters, mostly whites. This one was pretty easy - Obama bombarded the airwaves with TV ads portraying Romney as a corporate asset-stripper who cackled merrily all the way to the bank as he shipped blue collar jobs to Mexico and China. Obama also reminded them about the auto bailout he engineered, which saved many blue collar jobs in those parts of the country.
In Ohio and PA, as well as places with low minority populations, like Wisconsin and Iowa, Obama relied on the female vote. He associated Romney with Senate candidates like Richard Mourdock and Todd Akin, who made controversial remarks about abortion and rape. I believe Paul Ryan made some similar comments as well. He played up the angle that Republicans want to tell women what they can and can't do with their bodies.
0: http://www.nytimes.com/2012/11/08/us/politics/obama-campaign...