Wallace's first question to both candidates was on the Supreme Court. He asked why Trump believes he is right in confirming a justice before the election and why Biden believes he is right in saying the decision should wait until after Election Day.

"I will tell you very simply, we won the election. Elections have consequences," Trump said. "We have the Senate, we have the White House and we have a phenomenal nominee respected by all top top academic good in every way, good in every way."

"And by the way, the Democrats, they wouldn't even think about not doing it if they have -- the only difference is to try and do it faster. There's no way they would give it up. They had Merrick Garland, but the problem is they didn't have the election so they were stopped."

When the question was given to Biden, he said that the American people have a right to say who the Supreme Court nominee should be and that that nomination should wait until the November election concludes as Americans have already begun voting.

"It's just not appropriate to do this before this election," Biden said. "Roe v. Wade and the Affordable Care Act could both be struck down by a conservative Supreme Court."

Multiple Senate Democrats are refusing to meet with Trump's nominee, Amy Coney Barrett, citing the impending election, and have expressed mounting concern with her stance on health care as the Supreme Court is set to hear arguments on the fate of the Affordable Care Act one week after the election.

Senate Republicans, meanwhile, are moving ahead with the nomination despite claims they made in 2016 about not confirming Garland during an election year.

The first presidential debate of 2020 between Trump and Biden kicked off from Case Western Reserve University and the Cleveland Clinic in Ohio with moderator Chris Wallace of Fox News.

Trump and Biden skipped a handshake, customary at the top of such events, due to the coronavirus precautions. Each walked out to his respective lectern without masks.

The candidates will not deliver opening statements. Instead, the debate has been divided into six roughly 15-minute segments on the following topics selected by Wallace: Trump's and Biden's records, the Supreme Court, COVID-19, the economy, race and violence in U.S. cities, and the integrity of the election.

The entire audience -- already limited in its size -- has been tested for COVID-19.

ABC News Chief Anchor George Stephanopoulos said the main question is whether the candidates will do anything in this debate to change the course of this race.

Editor-in-Chief of FiveThirtyEight Nate Silver said that this presidential race is a "much less close race than it was four years ago."

Biden deputy campaign manager Kate Bedingfield fired back at Donald Trump Jr. -- who did an interview with ABC News ahead of her -- saying the president's son continues to deliver personal attacks on the vice president instead of making the case for why Trump should be reelected.

"I was listening to Don Jr. and I didn't hear a whole lot of reasons to vote for Donald Trump," Bedingfield said. "I heard a lot of attacks. I heard a lot of personal criticisms of Joe Biden's son. I didn't hear a whole lot of reason -- if I'm a voter sitting tonight, listening to this debate -- I didn't hear a lot of reasons to vote for Donald Trump."

Bedingfield said Biden will offer a different choice for voters of a leader focused on the issues, not on attacks, and she said success for the evening will be defined by Biden's ability to connect with "families at their kitchen table."

"He's going to be laying out a concrete vision to make life better for people across this country and I think that the clear contrast between somebody who views the world through the lens of having grown up in Scranton, Pennsylvania, versus somebody who views the world through the lens of Park Avenue is going to be very apparent on the stage tonight," she added.

TRUMP'S STATEMENT: "Every year, I get the call, 'California's burning. California's burning.' If that was cleaned, if you have forest management, good forest management, you wouldn't be getting those calls."

FACT CHECK: Trump's repeated comments connecting forest management and wildfires ignores the increasing impact on climate change on how quickly the fires develop and spread.

Trump has focused on forest management when talking about wildfires in western states, often criticizing local leaders who have disagreed with his response to climate change.

While decisions about how to manage forests and wildfires are important, Trump's stance disregards evidence that climate change is playing a significant role in why wildfires have become so destructive in recent years.

During a briefing on wildfires in California earlier this month Trump refuted State Secretary for Natural Resources Wade Crawfoot when he described the impact of increasing heat and drought on the conditions that lead to fires. Trump said, "It'll start getting cooler," directly contradicting conclusions by climate scientists who argue temperatures around the world will continue to rise by saying, "I don't think science knows actually."

Increasing heat and droughts are "supercharging" wildfires by creating drier conditions for trees and brush. Warmer temperatures have also decreased moisture from melting snow and allowed bark beetles to travel further north, killing millions of trees, according to the National Climate Assessment published in 2018.

These factors allow fires to spread more quickly.

As the planet continues to warm, those conditions will only get worse, making wildfires more dangerous, climate scientists say.

The majority of land impacted by wildfires in states like California, Washington and Oregon is also managed by the federal government, which proactively removes dead trees and brush and conducts controlled burns to keep forests healthy.

-ABC News' Stephanie Ebbs