In his New York Times magazine article, “Data You Can Believe In The Obama Campaign’s Digital Masterminds Cash In” Jim Rutenberg illuminates some of the strategies and techniques deployed by the Obama campaigns digital wizards in 2012.
With respect to ad-buying, Rutenberg explains:

… The campaign recruited the best young minds in the booming fields of analytics and behavioral science and placed them in a room they called “the cave” for up to 16 hours a day over the course of roughly 16 months. After the election, when the technology wizards finally came out, they had not only helped produce a victory that defied a couple of historical predictors; they also developed a host of highly effective marketing techniques that were either entirely new or had never been tried on such a grand scale.
Grisolano and McLean and the others were part of a singular breakthrough in the field of television-ad buying, where about 50 percent of the campaign’s budget was spent, or more than $400 million. Previous campaigns would make decisions about how to direct their television-advertising budgets largely based on hunches and deductions about what channels the voters they wanted to reach were watching. Their choices were informed by the broad viewership ratings of Nielsen and other survey data, which typically led to buying relatively expensive ads during evening-news and prime-time viewing hours. The 2012 campaign took advantage of advanced set-top-box monitoring technology to figure out what shows the voters they wanted to reach were watching and when, resulting in a smarter and cheaper — if potentially more invasive — way to beam commercials into their homes. The system gave Obama a significant advantage over Mitt Romney, according to Democrats and many Republicans (at least those who were not on Romney’s media team).
…Grisolano told me that the campaign literally knew every single wavering voter in the country that it needed to persuade to vote for Obama, by name, address, race, sex and income. What’s more, he hinted, the campaign had figured out how to get its television advertisements in front of them with a previously inconceivable level of knowledge and accuracy.

Regarding data-collection and classification:

Wagner dismisses the notion of “romantic war rooms” operating on political gut instinct as outdated and misguided. His is a hard-data system that rejects anything that is not definitively quantifiable. In the Bush era, strategists boasted about how they could predict voter behavior based upon car and sport preferences, a well-publicized bit of political magic that captured the imaginations of politicians and journalists alike. Wagner’s approach, part of a broader move in politics, cut all of that out; why engage in such divination when you have the time and money to just call voters and ask them about their leanings directly? “We’re trying to predict political preference; we’re not trying to predict whether you buy a car,” Wagner says dismissively.
The campaign couldn’t call the more than 150 million registered voters, obviously. But they could call enough of them in swing states (up to 11,000 a night) to figure out how they — and other people who lived near them, looked like them and earned like them — were likely to vote with an increasing degree of accuracy. In 2008, Wagner and his small team combined information from those calls with any other data they could find — census data, state voter lists and the like — and fed it into algorithms that produced support scores. One ranked how likely swing-state voters were to support Obama on a scale of 0 to 100, and another ranked how likely they were to show up at voting booths. Those scores helped the campaign direct resources toward the right voters, and Obama beat John McCain by 7 percentage points.

Rutenberg explains that the team developed an even more robust and sophisticated analytics system, “using bigger computer servers, better data on the nation’s voting-age population and more precise algorithms.” He notes also that the team developed a clever data mining strategy for facebook:

…When people opted to do so, they were met with a prompt asking to grant the campaign permission to scan their Facebook friends lists, their photos and other personal information. In another prompt, the campaign asked for access to the users’ Facebook news feeds, which 25 percent declined, St. Clair said.
Once permission was granted, the campaign had access to millions of names and faces they could match against their lists of persuadable voters, potential donors, unregistered voters and so on. “It would take us 5 to 10 seconds to get a friends list and match it against the voter list,” St. Clair said. They found matches about 50 percent of the time, he said. But the campaign’s ultimate goal was to deputize the closest Obama-supporting friends of voters who were wavering in their affections for the president. “We would grab the top 50 you were most active with and then crawl their wall” to figure out who were most likely to be their real-life friends, not just casual Facebook acquaintances. St. Clair, a former high-school marching-band member who now wears a leather Diesel jacket, explained: “We asked to see photos but really we were looking for who were tagged in photos with you, which was a really great way to dredge up old college friends — and ex-girlfriends,” he said.
The campaign’s exhaustive use of Facebook triggered the site’s internal safeguards. “It was more like we blew through an alarm that their engineers hadn’t planned for or knew about,” said St. Clair, who had been working at a small firm in Chicago and joined the campaign at the suggestion of a friend. “They’d sigh and say, ‘You can do this as long as you stop doing it on Nov. 7.’ ” (Facebook officials say warning bells go off when the site sees large amounts of unusual activity, but in each case the company was satisfied the campaign was not violating its privacy and data standards.)

“By March 2012,” writes Rutenmberg, “Wagner’s team had a workable list of what it deemed to be the most persuadable voters — in total, roughly 15 million of them in the swing states. Messina ordered the campaign to direct a majority of its efforts toward winning them back, one by one if necessary.” Noting that “The Internet, and specifically social media, may have fundamentally changed politics, but there is still nothing with the power to enrage or inspire like a well-produced television ad (see “47 percent, Romney”),” Rutenrberg adds:

The 2012 Obama campaign knew it had to be especially efficient in buying television time because it expected to be outspent by the combined forces of the Romney campaign and super PACs, including the American Crossroads organization, co-founded by Karl Rove.
“If we had to withstand being outspent — and nobody wanted to withstand it — but if we had to, we could tolerate being outspent with the people who have basically already made up their mind for us or the people who made up their mind against us,” Grisolano said. “But we were going to make sure that we put the full power of our buy with the people who were swing voters, who were on the edge. So, my task became, how do you create the tools you need to make that a reality?”
…The concept for the “optimizer,” as it was known in the campaign, was born: a system that could determine with more precision than ever what swing voters were watching in the greatest concentrations and how to get commercials in front of them in the cheapest advertising time slots possible….the optimizer helped it do what most strategists deemed impossible in a campaign between two well-financed opponents — talk to undecided voters through television advertisements on shows on which the opposition was not running a countermessage…In all, Obama ran nearly twice as many cable ads as Romney did, 588,006, on more than twice as many channels, 100, according to analysis by NCC Media, which helped both campaigns place spots…In the end, an analysis by the Republican ad-buying firm National Media found that Obama paid roughly 35 percent less per broadcast commercial than Romney did. Kantar Media CMAG, an ad-monitoring firm, showed that Obama and his supporting super PAC got nearly 40,000 more spots on the air than Romney and his super PACs did despite spending roughly $90 million less.

Rutenberg also writes about the extraordinary progressive social change commitment of the young men and women who staffed the Obama campaign’s data-driven effort. It’s a thing of the heart that the Republicans are going to have difficulty replicating in service to a political party whose central priority is tax cuts to fatten only the coffers of the rich.
Unfortunately, some of the key players of the Obama team won’t be involved in the 2014 congressional elections. We can hope, however, that their template can be emulated to some extent — at least enough to help Dems pick up seats in the House and hold the Senate.