Every race has its intricacies. Polling data compiled for both parties, for outside groups, and by independent surveys shed light on the kinds of voters who will tip the election in each state.
Former Democratic Gov. Tim Kaine sees an opportunity to attract two handfuls of Romney voters in Virginia. Women in the Richmond suburbs who fondly recall Kaine's time as governor appear marginally more likely to choose him than Obama. And men in the Northern Virginia suburbs, voters who care about transportation issues as much as anything else, might be inclined to register their disapproval of Obama -- especially with the pending budget sequester threatening defense industry jobs -- but also to stick with Kaine. In both cases, these Romney voters will likely view the Senate contest as a matchup between two well-known political figures in the Commonwealth, Kaine and Republican former Sen. George Allen, rather than between two candidates defined only by party labels. Romney, Democrats believe, has a wider appeal than does Allen.
Polling shows that voters choosing Romney and Kaine are disproportionately representative of a younger generation. More than 6 in 10 ticket-splitters are under 50 years old, while the electorate as a whole is split evenly between those over and under 50. Most ticket-splitters are self-identified independents, with whom Kaine outperforms Obama.
In Nevada, GOP Sen. Dean Heller has done an admirable job cutting into the base that Democratic Rep.Shelley Berkley needs to build. Private polling shows that more than 6 in 10 voters who say they will vote for Obama and Heller are women, while a disproportionate number are Hispanic and younger.
Public polling backs up at least some of those private numbers. A Latino Decisions/America's Voice poll conducted Sept. 22 to 28 shows Obama attracting 78 percent of Hispanics, while just 58 percent said they would back Berkley. Heller outperforms Romney by 9 points in that survey of 400 registered Latino voters.
Former Surgeon General Richard Carmona, a Democrat running for retiring Sen. Jon Kyl's seat in Arizona, is polling neck and neck with Republican Rep. Jeff Flake in a state that hasn't elected a Democratic senator since Dennis DeConcini won reelection in 1988. Carmona is competitive because a disproportionate number of women, Republican, and older Romney voters are backing him.
Private polling indicates that more than three-quarters of ticket-splitting voters here are over age 50, a group that makes up 59 percent of the electorate as a whole. And 42 percent of the small sample of crossovers are Republicans, versus about 3 in 10 of the electorate at large.
Massachusetts' Brown has been perhaps the most aggressive at targeting ticket-splitters. He will need it: Polls show Obama's support there hovering between the mid-50s and the low-60s, meaning Brown will have to convince a large number of Obama voters to back him over Democrat Elizabeth Warren.