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.
Mara LiassonSenate 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.
Mara Liasson[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?
Mara LiassonAs 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.
Mara LiassonThe aftermath of this extraordinary election [2016] could be just as surprising as the race itself.
Mara Liasson[Donald Trump ] would make history in so many ways because he is a candidate who eschewed the traditional arts of political campaigns, including field organization, traditional advertising, debate preparation and policy knowledge.
Mara LiassonThe base has chosen or is choosing a candidate that the establishment says is absolutely unacceptable. And what that means is this marriage of an elite, big business-backed establishment and a blue-collar, downwardly mobile base has really come to a divorce.
Mara LiassonYes, the presidential race is very close, and some public polls show it getting closer as we go into the final hours, but in one sense it's actually been stable for months.
Mara LiassonRepublicans 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.
Mara Liasson[Mike] Bloomberg aides says he's more likely to run if it's [Donald]Trump or [Ted] Cruz versus Sanders, then there would, presumably, be space in the middle for him. But he's less likely to go if Hillary Clinton is the nominee.
Mara LiassonHillary 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.
Mara LiassonThere's a lot of anxiety about terrorism among the country at large. There's also a feeling the country has stagnated.
Mara LiassonIf [Donald] Trump wins narrowly, Democrats can blame the loss on FBI director James Comey, who inserted himself late in the campaign in an unprecedented way.
Mara LiassonOn 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.
Mara LiassonFor a long time, many Republicans thought if they just took two aspirin and laid down, [Donald] Trump would go away.
Mara LiassonRomney still enjoys the Republicans' traditional advantage among voters who are veterans, but the Obama campaign is confident it can chip away at that.
Mara LiassonAfter months and months at the top of the polls, there is a real possibility that Donald Trump could be the nominee.
Mara LiassonAfrican-American voters are not nearly as enthusiastic about [Hillary] Clinton as they were about [Barack] Obama.
Mara LiassonIf 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.
Mara LiassonDonald Trump is a candidate who divided his own party more deeply than any presidential candidate has before.
Mara LiassonThe 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.
Mara LiassonRepublicans like Trent Lott, saying [Donald] Trump would be more flexible [then Ted Cruz].
Mara LiassonJeb Bush was supposed to be the establishment candidate, but he didn't catch on. And the extraordinary thing about this Republican primary is that the establishment, moderate wing of the party has sidelined itself. They're not coalescing around one candidate as they have in the past.
Mara LiassonWhite 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.
Mara LiassonYou have [Donald] Trump and [Ted] Cruz battling it out, and the moderate establishment candidates like Chris Christie or Jeb Bush, Marco Rubio, John Kasich - they have formed a circular firing squad.
Mara LiassonBoth 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.
Mara Liasson