Polls consistently show Donald Trump is running behind Hillary Clinton. After Labor Day, if Trump wants to find any solace, he needs to look to some of the races -- most of which were more competitive at this point -- where the polls tightened by early September and candidates were able to mount strong comebacks.
Some examples that have been frequently cited include Harry Truman against Thomas Dewey in 1948, Hubert Humphrey against Richard Nixon in 1968, Gerald Ford against Jimmy Carter in 1976 and Ronald Reagan against Carter in 1980, though in two of these cases the comeback did not produce victory.
At this point in the 2016 campaign, odds are that only something big will be able to dramatically shift the campaign and throw the Clinton-Trump race in a different direction.
The presidential debates, slated to start September 26, would be the first place to look. Though the impact of debates tends to be overrated, this fall they could potentially have a huge effect.
These debates could be unlike any we have seen before. The audiences that will tune in or log on to see Clinton take on Trump will probably be astronomical.
Trump's unorthodox approach to these events, as we saw in the Republican primaries, means that anything can happen. His style could be so unsettling that the debates push Clinton into making statements or physically acting in ways that damage her standing. Or his attacks could be so vicious that they start to undercut her support.
On the other hand, Trump's performance could be so outlandish that the debates simply propel the downward trajectory of his polls, confirming to viewers that he is unfit to be president.
October data dump?
Then there is the so-called October Surprise. This is a concept has been around since the 1960s and refers to a deliberate action that takes place with mere weeks left in the campaign, often by the president of the United States, to shift the election's direction.
In 1980, the year the term became popular, Reagan's campaign was terrified that President Carter would announce a deal had been reached in the Iran hostage crisis, bolstering Carter's re-election prospects.
But the October Surprise has usually turned out to be a bust, a conspiracy imagined.
This year, the October Data Dump, rather than the October Surprise, is what both candidates should fear most. It's possible to imagine a WikiLeaks-like revelation that leaves Clinton officials struggling to protect their position or Trump facing a defeat even worse than imagined.
With the possibility that state actors like Russia are now seeking to influence U.S. elections through hacking, the possibilities are frightening. Just as social media has created new opportunities for candidates to communicate directly to voters without any intermediaries, the Internet has created the kind of electoral uncertainty that we have not seen before.
The decision by the Republican Party about what to do with its resources can also have huge ramifications. There have been a number of reports about how party officials are vacillating between continuing to support Trump, who is relying on them almost entirely for the most basic operations of his campaign, or throwing everything toward Senate and House candidates so to avoid losing control of every branch of government.
If the Republicans abandon Trump after Labor Day, that decision could be extremely important. With several third-party campaigns up and running, a congressional centered election by the Republicans could be effective if GOP voters have someone else to cast their ballot for besides Clinton.
Even though it would probably make a Trump victory impossible, a shift in resources may produce the kind of divided government in 2017 that would prevent a President Clinton from advancing a significant agenda, along with contentious political conditions that will result in ongoing investigation and scandal warfare.
With Trump as the nominee, there is also the serious potential for a total meltdown at the top of the ticket that could produce the kind of landslide we haven't seen in decades. He is the great unknown. Already there have been many moments, from his comments about women and immigrants to his associations with right-wing extremist organizations, that create the potential for his campaign to fall apart.
Thus far he has avoided that outcome at every turn, but that won't mean this can't happen. Trump's unpredictable and uncontrollable style means that the teleprompters will only hold him back for so long.
The networks of "alt right" organizations that have been in the orbit of his campaign provide more than enough opportunities for something truly shocking to come out. If any of this occurs, the landslides of yesteryear might just happen again.
Game changes are rare
But even with all of these factors, the odds remain very low that there will be any fundamental change in the basic dynamics of the campaign. For all the talk of "game change" moments in campaign memoirs, these turning points are rare.
Right now it looks like Trump is headed toward a real electoral disaster for the GOP. When states like Utah and Georgia are not locks for the Republican nominee, the party is in real trouble. As Laura Meckler reported in the Wall Street Journal, Trump's increasingly narrow path to victory
would have to include winning in Ohio, Florida, Pennsylvania and North Carolina.
"It just becomes very hard and difficult to understand how the Trump campaign gets to 270," said one of Mitt Romney's 2012 strategists.
The kind of landslide victories that candidates like FDR in 1936 and LBJ in 1964 enjoyed might no longer be possible, given that the electorate is so polarized in many states. But Clinton holds a strong lead in most of the key battleground states and there is little evidence that Trump can "turn" blue states into red.
Even if there was a major national security or domestic crisis in September or October, it is unclear that public opinion would shift dramatically given that neither candidate is the incumbent and the polls show strong levels of confidence in Hillary Clinton on a number of key issues. It is possible to imagine, for example, that an unsettling foreign policy situation leaves more voters more comfortable with the kind of experience that she offers rather than Trump.
The bottom line is that no one knows what's around the corner. One thing is that this is unlike any campaign we have ever seen. So the weeks after Labor Day will surely be filled with surprises, twists and turns, nasty moments, and a raucous political fight that will make some viewers think they are tuned into the 2016-2017 NFL season rather than presidential politics.