Here are some hot-button issues that haven't been discussed in the tickets' first two debates:
Clinton's role as secretary of state at the time of the 2012 attack on the U.S. consulate in Benghazi, Libya, and the questions that have been regularly and repeatedly raised about her involvement have kept the issue alive for the past four years.
It has been a regular talking point among her critics, but neither Trump nor his running mate, Indiana Gov. Mike Pence, mentioned it.
The Supreme Court
Neither his name nor the Supreme Court vacancy came up in either of the debates, and if the Senate continues to run out the clock on the Obama administration, the appointment could be one of the first actions of the next president.
At one point during this campaign, Trump said he would be "fine" with putting Americans on trial at the military base, but it has yet to be discussed on the debate stage.
But the latest news of another NSA contractor who allegedly leaked documents could bring the issue to the forefront of the next debate.
Several Social Issues
Same-sex marriage, as well as gay and transgender rights, did not come up in either debate. The legalization of marijuana has also not been addressed.
Abortion is a historically controversial issue, and it has been at points during this campaign. So it has surprised many political observers that the only time it has come up so far was on the vice presidential debate stage, when Pence was asked to cite an instance when he struggled to balance his faith with a policy position.
2 Topics Briefly Touched On
Similarly, there have been no concrete details or descriptions of the candidates' views on how to improve veterans' affairs and the lives of returning service members. The only times it was mentioned came when Kaine accused Trump of not supporting veterans and Pence responded, "Donald Trump supports our veterans."