Republican candidates have won whites with college degrees in every presidential election since polling began.

If Pat Toomey of Pennsylvania wins, for instance, it will tell Republicans that their own brand hasn't been hurt too badly by [Donald] Trump's negatives.

The president is under 50 percent approval ratings in all the battleground states. So, you could say that President Obama is defying gravity by still being in a dead heat with Mitt Romney. And one of the reasons that he is, is because the changing face of the electorate are giving him a small boost.

Senate races have tightened along with the presidential race. Watch to see how many Republican Senate candidates outperform Donald Trump - and how many hang on to their seats in states that he loses.

Even if [Donald] Trump concedes, some of his supporters have promised to take up arms against [Hillary] Clinton.

The [Hillary] Clinton campaign's recent travel schedule shows how seriously it takes this problem. She and her surrogates have held rallies in cities like Philadelphia, Detroit and Cleveland, trying to boost turnout among African-Americans.

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.