TRUMP'S CLAIM: "Through John, who is -- John Ratcliffe, who is fantastic, DNI. He said the one thing that's common to both of them (Russia and Iran), they both want you to lose because there has been nobody tougher to Russia with -- between the sanctions. Nobody tougher than me on Russia."

FACT CHECK: While it is unclear whether Trump's director of national intelligence, John Ratcliffe, told him personally that Russia hopes he would lose the upcoming election, such a statement would contradict what the U.S. intelligence committee has determined.

In August, the Office of the Director of National Intelligence assessed "that Russia is using a range of measures to primarily denigrate former Vice President Biden and what it sees as an anti-Russia 'establishment.'” The office has never stated publicly that Russia hopes Biden will lose the upcoming election.

As for Iran, the office said it determined the country in its interference efforts "seeks to undermine U.S. democratic institutions, Trump, and to divide the country in advance of the 2020 elections."

Ratcliffe in a Wednesday evening news conference revealed both Iran and Russia recently obtained voter registration data in their efforts to interfere in the 2020 election, and that Iran was separately behind "a series of threatening emails that were found to be sent this week to Democratic voters," which he said was "designed to intimidate voters, incite social unrest and damage President Trump."

But Democratic leaders have argued Ratcliffe may have inflated Iran's motivations relating to Trump and instead the country was seeking more broadly to sow chaos in the U.S. democratic process.

U.S. officials have also characterized to ABC News that Russia’s interference efforts both in 2016 and 2020 far exceed that of Iran’s in both scope and complexity.

-ABC News' Alexander Mallin

Climate change -- a hot-button topic for years -- has taken on renewed significance ahead of the 2020 presidential election, with wildfires decimating the West, tropical storms pounding the Gulf Coast and year after year of record temperatures.

Both Trump and Biden largely toe their respective party lines when it comes to issues pertaining to environmental policy.

Throughout his presidency, Trump reversed many American commitments to mitigating climate change, most notably pulling out of the Paris Agreement, removing clean water protections and seeking to fast track environmental reviews of dozens of major energy and infrastructure projects, such as drilling, fuel pipelines and wind farms.

Biden has countered the Trump administration's policies by promising to protect the environment with a proposed a $5 trillion plan.

Here is where each candidate stands on the issues

Trump responded to a question on the impact of his language on racial conflict in the country by touting his work on criminal and prison reform as well as opportunity zones.

"It makes me sad, because I am, I am the least racist person," Trump said. "I can't even see the audience because it's so dark, but I don't care who's in the audience, I'm the least racist person in this room."

Biden responded by saying that the president "pours fuel on every single racist fire, every single one."

When asked about his previous support for crime bills in the 1980s and 1990s, Biden said again that his support was "a mistake."

"I've been trying to change it since then, particularly the portion on cocaine," he said. "That's why I've been arguing that, in fact, we should not send anyone to jail for a pure drug offense. They should be going into treatment across the board."

Trump asked why Biden couldn't change those policies during his time as vice president. 

"Why didn't you get it done? See? It's all talk, no action with these politicians," he said. "Why didn't he get it done? That's what I'm going to do when I become president -- you were vice president along with Obama as your president, your leader, for eight years. Why didn't you get it done?

Biden brought up the Obama administration's work to release 38,000 federal prisoners and grant clemency. After continuing pressing from Trump, Biden said they couldn't get more done because "we had a Republican congress."

The final topic of the night was climate change with Welker first asking each candidate how he would combat climate change and support job growth at the same time as president. Trump answered first. 

"So we have the trillion trees program. We have so many different programs. I do love the environment, but what I want is the cleanest, crystal clear water, the cleanest air," Trump said, taking credit for the country's reduced carbon emission last year. 

He went on to slam other counties air-quality and tout the U.S. by comparison. 

"Look at China, how filthy it is. Look at Russia. Look at India. It's filthy. The air is filthy. The Paris Accord, I took us out because we were going to have to spend trillions of dollars, and we were treated very unfairly," Trump said, closing his two minutes by saying his administration has done an incredible job "environmentally."

When it was Biden's turn, he pivoted to the existential threat he says global warming poses to humanity and said the U.S. has a moral obligation to "deal with it" -- but said climate change also creates a prime opportunity for new jobs. 

"Here's where we have a great opportunity. I was able to get both all the environmental organizations as well as labor, the people worried about jobs, to support my climate plan. Because what it does -- it will create millions of new good-paying jobs," Biden said. "Wall Street firms indicated that my plan -- my plan will, in fact, create 18.6 million jobs, 7 million more than his. This is from Wall Street. And I'll create $1 trillion more in economic growth than his proposal does. Not on climate, just on the economy."

Trump slammed Biden's response, claiming the former vice president's plan would cause a massive economic depression and deeming it a "pipe dream," before raising Biden's stance on fracking. 

In the face of Trump's criticisms, Welker asked Biden directly, "Would you rule out banning fracking?"

"I do rule out banning fracking," Biden said. "We need other industries to transition to get to ultimately a complete zero emissions by 2025. What I will do with fracking over time is make sure we can capture the emissions from the fracking, capture the emissions from gas. We can do that and we can do that by investing money. It's a transition to that."

"Excuse me," Trump interrupted. "He was against fracking. He said it. I will show that to you tomorrow."

"Fracking on federal land, I said," Biden responded. "No fracking and/or oil on federal land."