Republican voters are coalescing behind [Donald] Trump, but many Republican elected officials still say they can't support him.

Hillary Clinton is also not a very exciting, inspiring candidate to a lot of the left-leaning Democratic base, especially in Iowa.

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.

If they can get 15 or higher, it will be a very bad night for House Speaker Paul Ryan. Ryan twisted himself into a pretzel by endorsing but not always supporting Donald Trump. Now, he's facing the prospect of a slimmer majority, with fewer moderates. Conservative members in the Freedom Caucus have already sent warning shots threatening Ryan's tenure as speaker.

Both the Obama and Romney campaigns said they pulled all their political ads today in observance of the September 11th anniversary. But politics wasn't very far offstage. The Obama campaign sees foreign policy as an advantage this year.

If [Donald] Trump drags down a bunch of Senate Republicans, the post-election GOP assessment will be much more pessimistic.

The GOP establishment, in particular, is facing a pick-your-poison kind of decision. Many establishment Republicans dislike [Ted] Cruz personally. He has no Senate endorsements.