The result would seem to bear out the Democratic view, but as both books make clear, there's scant evidence that a different sort of Republican campaign would have led to a different outcome.

As Vavreck and Sides say, there were no "game changers" in the 2012 campaign but instead a lot of "game samers." The country began the election season divided between partisan camps and ended it that way. The economy grew slowly but fast enough to make the incumbent the favorite. The rare moments of drama — the videotape of Romney disparaging 47% of the population as "takers," Obama's listless performance at the first debate — actually moved relatively few voters and largely canceled each other out.

For both sides, the campaign was largely an effort to mobilize core supporters and get them out to vote. For candidates in a partisan era, that's the surest route to victory, and Obama's success at targeting voters will no doubt become the template for both parties. But, as Balz notes, that victory comes with a price that becomes more apparent with each passing month.

"The techniques used to motivate left and right are not ones designed ultimately to bring the country or the parties together once the election is over," he writes. Both candidates "operated within comfortable boundaries at a time of intractable problems."

Lauter is The Times' Washington bureau chief.

Collision 2012
Obama vs. Romney and the Future of Elections in America

Dan Balz
Viking: 400 pp., $32.95

The Gamble
Choice and Chance in the 2012 Presidential Election

John Sides and Lynn Vavreck
Princeton University Press: 352 pp., $29.95