Gallup has a demographic profile of likely voters this year, and it looks remarkably like what we saw in 2012.

Given the relatively similar demographic composition of the 2012 and 2008 electorates, the election's outcome may hinge more on how groups vote rather than to what extent they will vote. And most groups are currently less likely to support Obama now than they were in 2008. However, Obama's seven-point margin of victory in the 2008 election leaves him considerable breathing room to lose electoral support yet still win the election.

