According to the Real Clear Politics (RCP) Battleground State poll averages, President Obama leads in six of the eight most contested races. This matters, as Nate Silver of the New York Times explains because poll averages tend to accurately predict which candidate wins a battleground state, even if the margins are off slightly. However, there is a real possibility that the polls have systematically overestimated Democratic turnout in several of these key battleground states. For instance, the CBS/NYT/Quinnipiac poll found Obama with a five-point lead in Ohio, but their likely voter model assumes a +8 Democratic advantage in 2012, which happens to be exactly what it was in 2008. Although possible, it seems implausible that the Obama campaign could galvanize enthusiastic support in 2012 similar to the unprecedented level of support it had in 2008. In other words, if battleground state likely voter models in polls have systematically overestimated Democratic turnout, this could indicate a Romney win. In fact, as Nate Silver writes, the only way for Romney to win is if state polls are systematically biased.
Based on the polling data, here are a few potential electoral map scenarios. If Nate Silver's forecasting model is correct, we'd expect Obama to essentially sweep the battleground states, except for North Carolina, resulting in a landslide for Obama with 332 electoral votes to Romney's 206.
However, based on the polling data there is a very real possibility that Romney could take Colorado, Iowa, and New Hampshire, Virginia, and very likely Florida. Iowa Even the poll averages for Iowa overestimated Obama's margin in 2008 by a share larger than his poll average lead today. And with only a two point Obama lead in Iowa, it is entirely possible Romney could in fact win the state. Florida Although recent polls give Obama an ever-so-slight advantage in Florida, the RCP average has Romney winning the state. Virginia RCP indicates Obama's tenuous lead in Virginia with only a +0.3 percentage lead, suggesting Romney could very realistically take the state. New Hampshire polls pretty consistently find Obama the winner, except for an ARG poll which found the candidates tied. However, the Romney campaign's headquarters are just a few short hours away in Boston, MA and could arguably mount a formidable GOTV effort in New Hampshire on Election Day. Colorado is a right-leaning state, but that swung for Clinton in 1992 and Obama in 2008. Moreover, polls have shown vacillation between the two candiates. Nevada It is unlikely that Romney will win Nevada, despite it's swing state status and previous Republican presidential voting history. In 2008, poll averages underestimated Obama's actual vote margin over McCain by nearly five percentage points and Obama currently has about a 2.8 point lead.
Nevertheless, even Romney winning these additional swing states still ensures an Obama victory 271 to 267 electoral votes.
Ohio If Romney were to win the electoral college he would have to win one additional prized swing state, Ohio. RCP has Obama with an average 2.9 point lead suggesting Romney may fall short of winning the presidency. However, if the Ohio state polls' likely voter models fail to reflect actual turnout, Romney could win the state.
An Ohio win for Romney also makes winning other smaller battleground states less crucial. For instance, Romney could lose Iowa, New Hampshire, Nevada, and Wisconsin and manage an electoral victory of 275 electoral votes.
If Romney loses Ohio, it most likely spells out a win for Obama. However, there are several other paths for a Romney victory. For instance, if Romney sweeps nearly all the other swing states, except Wisconsin, he could lose Ohio and pull ahead with 273 electoral votes. However, a Nevada win seems incredibly unlikely.
There are a few game changers; one would be a Wisconsin win. Romney's vice presidential pick Paul Ryan heralds from the Badger state. Ground game infrastructure is also still intact six months after Republican Gov. Scott Walker withstood a fierce recall election after he tried to reform public employee unions in the state. However, Obama continues to lead in the state with a 4-point RCP average advantage, while only Rasmussen has found the race tied. Also, Wisconsin rebounded faster for Obama after his Denver-debate debacle. Romney would also have to pick up New Hampshire or Iowa in combination with Wisconsin to withstand an Ohio loss.
Another remote possibility, but certainly a game changer would be a Pennsylvania win for Romney. Pennsylvania, like Ohio, is electorally rich. However, Pennsylvania hasn't voted for the Republican presidential candidate since 1988. Clinton effectively turned the state blue, and Republicans haven't been able to flip it since. However, a Tribune-Review/Susquehanna poll of 800 likely voters found the race tied and RCP has Obama's average at +3.8 points. We've also seen the Romney campaign ramp up advertising in the state. If there were nothing for the Obama campaign to worry about, they wouldn't have sent out campaign surrogate Bill Clinton to the state in response. But as David Axelrod has said he'll shave off his mustache if Obama loses Pennsylvania, Michigan, or Minnesota on Election Day.