National and state poll results have been at odds over the past week, with nationwide surveys declaring a slight advantage for Republican challenger Mitt Romney, and many swing state polls showing President Obama holding on to a lead in critical states. Which viewpoint is correct?
Since the first presidential debate, Romney has risen precipitously in national polls, due to his aggressive and passionate performance, which resonated with independents and undecided voters. Obama, however, was widely viewed as meek. And thus began a week and a half of shifting fortunes, as Romney made up his nationwide deficit and eventually overtook the president in several prestigious polls.
This was an unprecedented late-campaign comeback, and it was difficult to see how long Romney's post-debate "bounce" would last.
With Romney 4 points ahead of Obama nationwide in one Pew Research Center Poll, and 1 or 2 points ahead in other polls, Romney's momentum began to move the needle in swing states like Florida, Colorado and Virginia.
He is now ahead in North Carolina, with small leads in Virginia and Florida, though Obama seems to have edged back into the lead in Colorado.
Obama still leads in Ohio, perhaps the most crucial swing state. No Republican has ever won the White House without winning Ohio, though several increasingly difficult paths to victory without Ohio do exist for Romney. The state is not a must-win, but it will make his job much easier.
Due to the odd math of the Electoral College, whichever candidate wins each state receives all of its votes, so this election may see one of those rare instances when one candidate wins the popular vote nationwide, but still loses the Electoral College, and therefore the presidency.
While unlikely, it happened as recently as 2000, when George W. Bush lost the popular vote to Al Gore but took Florida's electoral votes and the victory.
It may help to look at all polls in aggregate, rather than just the latest polls. While Romney is trending up lately, Obama had a long string of success prior to two weeks ago, and that increases the probability that Romney's recent rise will abate.
FiveThirtyEight still has Obama at a 63.3 percent chance of winning, though that is down over 15 percent since last week.
Intrade, one of the world's largest speculation markets, still has Obama's odds at nearly two-thirds.
But this election has taken unexpected turns, and may take several more. Conventional wisdom says debates make little difference of the outcome of an election, but Romney gained nearly 5 points in the national polls after his first debate.
If voters are still persuadable at this last stage in the campaign, it's very possible that one or both of the remaining presidential debates will swing the electorate in a different direction.
At this point, the odds are still in Obama's favor. National polls show him regaining some of the ground he lost, and that will likely be reflected in swing state polls in the next few days, which should tip a few of them back into his corner.
Of course, the biggest variable is still Tuesday's debate. Obama and Romney will have another chance to speak directly to the American public, and whichever one learned the lessons of the last debate the best will likely take the lead, and perhaps the election.
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