The showdown came as President Donald Trump and several in his orbit have tested positive for the novel coronavirus, raising questions on a transfer of power to the vice president were Trump at 74 -- or Democratic nominee Joe Biden at 77 -- to become too ill to serve.
The debate's format was divided into nine 10-minute sections with each candidate having two minutes to respond to the opening question in each segment and the remaining time allowed for follow ups. Moderator Susan Page, Washington Bureau chief of USA Today, did not release the topics in advance.
The sole vice presidential debate follows Trump and Biden's chaotic debate last week in Cleveland.
Here is how the news is developing today. All times Eastern.
Oct 07, 2020, 10:19 PM EDT
Trump tweets praising Pence for doing ‘great’
Trump tweeted in support of Pence saying he is, "doing GREAT" and Harris, calling her a "gaffe machine," a criticism he uses often to attack her running mate Joe Biden.
Biden has also tweeted in support of his running mate during the debate, saying that Harris is "showing the American people why I chose her as my running mate."
Oct 07, 2020, 10:15 PM EDT
Pence talks about the death of Kayla Mueller in ISIS custody
In speaking to American leadership, Pence brought up the case of Kayla Mueller, a humanitarian worker from Arizona who was kidnapped by the Islamic State in Syria in 2013 and died in the terror group's custody.
Mueller's parents were in the debate's audience as Pence's guests and appeared last month at the Republican National Convention.
Guests of Vice President Mike Pence Mike Pence, Marsha and Carl Mueller, parents of Kayla Mueller, wait for the start of the vice presidential debate, Oct. 7, 2020, in Salt Lake City.
Eric Baradat/AFP via Getty Images
Pence suggested former President Barack Obama and Biden carried blame for Mueller's death, saying they "hesitated for a month" while she was held captive.
Harris, in her response to the topic of American leadership, first addressed Mueller's family.
"First of all, to the Mueller family, I know about your daughter's case and I'm so sorry. I'm so sorry. What happened to her is awful and it should have never happened," Harris said. "And I know Joe feels the same way. And I know that President Obama feels the same way."
Oct 07, 2020, 10:13 PM EDT
Harris on American leadership: 'It's about relationships'
In a discussion of foreign policy and the role of American leadership, Harris brought up Trump’s handling of the Iran nuclear deal and criticized the president's “unilateral” approach.
“He's walked away from agreements,” she said. “We were in the Iran nuclear deal with friends, with allies around the country. And because of Donald Trump's unilateral approach to foreign policy, coupled with his isolationism, he pulled us out and has made America less safe.”
“So, Susan, it's about relationships and the thing that has always been part of the strength of our nation, in addition to our great military, has been that we keep our word,” she added. “But Donald Trump doesn't understand that because he doesn't understand what it means to be honest.”
Oct 07, 2020, 9:56 PM EDT
Harris says Trump administration ‘lost’ trade war with China
On the issue of jobs, Harris took aim at the Trump administration trade policy with China.
“You lost that trade war. You lost it. What ended up happening is because of a so-called trade war with China, America lost 300,000 manufacturing jobs,” Harris said. “Farmers have experienced bankruptcy because of it. We are in a manufacturing recession because of it.”