The one thing most haven't mentioned if it looks like it will be a huge landslide in the Presidency do you start to see voters looking at electing a strong opposition. Remember Clinton despite being well ahead is still not particularly well liked or trusted by a majority of voters. I think you may see an effect where in Atlas blue states like Missouri, Indiana where voters become more interested in keeping Clinton accountable by supporting the Republican candidate. This probably will be less of a factor in Wisconsin, Illinois, NH, Nevada though and Democratic held Senate seats. Not suggesting it will play a huge roll but I think this could still be in play.
Almost all of the voters thinking this way will likely vote for Trump anyway.
The voters most likely to take that stance are independents, and right now I don't think Trump is winning them.
Independents have recently voted for the same party down ballot as they do for President, which is why Senate races and the House vote have closely tracked that of the Presidential race since 2000. This isn't like the 1970s and 1980s when you had reliably Democratic voters switch to vote for Nixon and Reagan at the top of the ticket.
Speaking as an Independent, back in the 1970s and 1980s (and yes, I have been voting that long 
) it was much easier to find good candidates to vote for on either side of the aisle. If you vote for the best candidate in a race, regardless of party, it was quite common to go back and forth between parties as you worked down the ballot.
The increasing ideological purity of each party in recent years makes this much more difficult. The Republicans in particular have become quite extreme compared to a few decades ago. The Democrats have also started becoming more extreme, after a lurch back toward the center in the 1990s, but aren't as far from the center as the Republicans. (This is my perspective as a centrist, and I recognize that others might view it differently.) It's very difficult to find a centrist candidate that I truly like these days. However, in recent years I have more often voted for Democrats. This is because with polarized parties, the best way to find a middle ground is through compromise and consensus. The Republicans have become increasingly unwilling to do so.
Exactly my thoughts, reasonings and feelings as well. Thank you!
