The winner's margin of victory also matters. If it's a squeaker, that will make the lessons learned for both parties much murkier.

Romney still enjoys the Republicans' traditional advantage among voters who are veterans, but the Obama campaign is confident it can chip away at that.

Many people feel he did cross a line in a way he hadn't even done before and also that Republicans had to speak out because they believe Trump poses a danger to the party.

White voters were 72 percent of the electorate in 2012, and their share of the population has shrunk a couple points since then. [Donald] Trump has had trouble winning certain segments of the white vote, such as suburban women and college-educated voters.

If she Hillary Clinton win just two of the three big battleground states - North Carolina, Florida and Virginia - she will have shut off Trump's path to 270 electoral votes, even if he wins the other toss-up states.

The Senate is the big prize. Until recently, Democrats felt confident they could get the four seats they needed to take back control if [Hillary] Clinton is in the White House and Vice President Tim Kaine held the tie-breaking vote.

Donald Trump is a candidate who divided his own party more deeply than any presidential candidate has before.