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

BIDEN'S STATEMENT: "He (Trump) has executive orders that have no power. He hasn't lowered drug costs for anybody."

FACT CHECK: Trump signed an executive order in September aimed at lowering drug costs by trying to reduce the prices Medicare pays for prescription drugs, but experts have said it is unclear what authority the president has to carry it out.

His orders, if enacted, would lower drug prices by directing drugmakers to offer their medicines to Medicare at the same prices they do in other countries. However, the process is likely to take months, and court challenges should be expected.

Trump has promised several versions of this idea for nearly two years, and Department of Health and Human Services has never proposed rules for how this would work.

Also, in an analysis released earlier this month, GoodRx found drug prices are surging faster than any other medical service or good, increasing by 33% since 2014.

-ABC News' Elizabeth Thomas

At the end of the first presidential debate, which lasted 98 minutes, ABC News calculated the candidate's approximate speaking times:

Trump: 37:16
Biden: 35:22

Here's the time spent on each individual topic including moderator speaking time:

Trump and Biden records: 16:23
The Supreme Court: 14:56 
COVID-19: 15:24 
The Economy: 14:42, with 2:38 spent on Trump's taxes
Race and violence in our cities: 17:07 
The integrity of the election: 11:35

When asked by Wallace if he would urge his supporters to stay calm during the extended period after the election when ballots are still being counted, Trump did not give a definitive answer.

"I'm urging my supporters to go into the polls," Trump said.

"I am urging my people -- I hope it's going to be a fair election, if it's a fair election," the president continued.

"You're urging them what," Wallace interrupted.

"I am 100% on board, but if I see tens of thousands of ballots being manipulated, I can't go along with that."

"What does that mean?" Wallace pressed.

The president did not clarify. Trump has previously falsely claimed mail-in ballot fraud.

When Biden was asked the same question, he responded with a definitive, "yes."

"Here's the deal," Biden added. "The fact is I will accept it, and he will too. You know why? Once when the winner is declared after all the -- after all the ballots are counted -- all the votes are counted, that'll be the end of it."

Biden finished by saying he will "support the outcome" either way.

President Donald Trump is set to enter the first presidential debate on Tuesday down in the polls, but coming off the high of nominating his third Supreme Court justice. Some top advisers expect a dominant performance by the president, despite the opposing narratives of attacks on Joe Biden's mental state and the Trump campaign's work to raise expectations for the Democrat ahead of the showdown.

With days to go the debate, Trump has carried out conflicting and confounding strategies both repeatedly targeting Biden's mental acuity, claiming at a recent rally he doesn't know he's alive, while also making passing attempts to boost the former vice president as a seasoned debater who could outshine him.

"This guy doesn't have a clue. He doesn't know where the hell he is," Trump told his supporters in Pittsburgh a week to the day before the first debate. "This guy doesn't know he's alive."

At a campaign rally Saturday night in Pennsylvania, the president both attacked Biden as "dumb" before immediately lauding him as an experienced debater. "He’s a dumb guy. Always known as a dumb guy. But we look forward to seeing him in the debate. He's got a lot more experience. He's got 47 years. I’ve got 3 1/2 years. So we'll see. But he's got 47 years of experience."

Biden has brushed off Trump's onslaught of attacks on his mental fitness. "Watch me, Mr. President. Watch me. Look at us both, what we say, what we do, what we control, what we know, what kind of shape we're in," the former vice president said when asked by ABC News about the president's attacks on his cognitive ability.

While some advisers tell ABC News they're nervous as the president enters his first debate since his encounters with Hillary Clinton four years ago -- with Biden having participated in nearly a dozen debates leading up to clinching the Democratic nomination -- others are anticipating a knockout performance by the president and expect the debate to help highlight the former vice president's gaffes, sources familiar said.

-ABC News' Will Steakin, Katherine Faulders and John Santucci