The Democrats pulled out one of their most powerful surrogates - and no, it wasn't President [Barack] Obama. Beyoncé showed up at a GOTV rally in Cleveland, joining her husband, Jay Z, and 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.
In 2012, African-Americans were 13 percent of the electorate, and 93 percent of them voted for [Barack] Obama.
African-American voters are not nearly as enthusiastic about [Hillary] Clinton as they were about [Barack] Obama.
[Hillary] Clinton has also struggled with key groups of voters.
This year [2016], however, polls show [Hillary] Clinton winning white college-educated voters by double digits.
Republican candidates have won whites with college degrees in every presidential election since polling began.
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.
What does [Hillary] Clinton do if she loses? Concede? Blame the Russians? Or the FBI?
Mitt Romney got 59 percent of the white vote in 2012, considered by many to be a high-water mark with this demographic group. Can [Donald] Trump win a higher share of white voters than Romney and get more of them to turn out?
The aftermath of this extraordinary election [2016] could be just as surprising as the race itself.
[Donald] Trump's path to victory depends on getting historic levels of support from white voters, and particularly large numbers of white, non-college-educated voters.
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.
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.
No one is predicting that the Democrats will get the 30 pickups they need to take back the House majority.
If [Donald] Trump drags down a bunch of Senate Republicans, the post-election GOP assessment will be much more pessimistic.
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.
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.
If [Hillary] Clinton can come close in those two traditionally red states, it will be because of the diverse, educated populations around Atlanta and Phoenix. And it will be a sign that Arizona and Georgia are on their way to becoming the new battleground states.
Meanwhile, there are some traditional battleground states - like Ohio and Iowa - that are becoming older, whiter and less educated. That's turning them from true battlegrounds into more reliable red states.
As those states and others in the South and West become more diverse and educated, they will become harder for the Republican Party - in its current form - to win.
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.
Democrats came into the race with a structural advantage in the Electoral College. Their big blue wall - the states that Democrats have won in the past six presidential elections - gave [Hillary] Clinton a strong base to build on.
In 2012, Hispanics were 10 percent of the electorate, underperforming their share of the voting-age population. Mitt Romney got 21 percent of their vote, and [Donald] Trump has been polling much lower than that.
If [Hillary] Clinton can't boost African-American turnout, even with all that help, the question becomes whether she can make up for it with historic levels of support from Hispanics and suburban women.