If [Donald] Trump loses narrowly, it will make it much harder for the GOP to unify. Under that scenario, the Trumpists are likely to argue that the election was lost because the Republican establishment failed to rally around the choice their own voters made.

On the other side, you have the conservative intelligentsia - magazines like National Review, which has a big anti-Trump issue; Weekly Standard editor, conservative talk show hosts - they're mounting a big anti-Trump effort, pro-Cruz effort because they think [Donald] Trump is dangerous and he's not qualified to be commander in chief.

Hillary Clinton has had a small but persistent lead since June - anywhere from 2 to 5 points. The stock markets and the election betting pools are predicting a Clinton win.

[Donald] Trump has said he will accept the results of the election - if he wins. And he has said the only way he can lose the election is if it's stolen from him. Weeks before any votes were cast, he was predicting widespread voter fraud. So if he loses, what does he do?

Republicans think that [Ted] Cruz would be like Barry Goldwater. He'd lose in a landslide and pull the party down with him. They'd lose Senate and House seats.

If [Hillary] Clinton wins, history will also be made: She would be the first female U.S. president, of course, but also the only candidate in the modern era, other than George H.W. Bush, who managed to follow a two-term president of her own party.

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.