Joe Biden said in an NBC town hall Monday night that he was not surprised President Trump contracted COVID-19.

What he's saying: "Quite frankly, I wasn't surprised," the Democratic presidential nominee said when asked by MSNBC's Lester Holt if he was surprised Trump had tested positive for the coronavirus.

• "For the last three months, three times a week, I'm on the telephone and on zoom with some of the leading immunologists in the nation, and they go through everything that's happening," Biden said.
• "So the idea that COVID does not spread in proximity when you don't have a mask on, when you're not socially distancing, when there's large groups of people, when you're inside particularly and even when you're outside, that's not surprising" he added.
• The former vice president reiterated his plan to implement to mandate that all people wear a mask on federal property.

Driving the news: Biden's comments came less than two hours after Trump departed the Walter Reed Medical Center on Monday evening to return to the White House via Marine One following three nights at the hospital for coronavirus treatment.

• Upon reaching the White House, Trump took off his mask and saluted Marine One as photographers encircled him. He then walked into the White House, still maskless.

Other key town hall takeaways:

• On last week's presidential debate: Biden said he was "trying to figure out how I could possibly have [Trump] respect the debate. Respect the evening. Respect the moderator. And get us an opportunity to speak.
• "The one thing that became absolutely clear... he didn't want to answer any questions. He did not want to talk about substance," Biden said.
• "It was all invective, all personal ... And I did get very frustrated. I did get frustrated. And I should have said this is a clownish undertaking instead of calling him a clown."

• On police reform: "We are going to bring all these interests together, peaceful protesters, police chiefs police officers, police unions, as well as a civil rights groups in the White House and sit down and decide what are the things that need to be done to improve and help police officers," Biden said.
• "I'm the only one who's talked about increasing police budgets ... In addition to that, I am also proposing that we spend a significant more money on community policing."
• On white supremacy: Biden said that one of the reasons he decided to run for president again was due to the "constant dog whistle" coming from Trump and his supporters.
• Biden pointed to the death of Heather Heyer, who was killed by a neo-Nazi in Charlottesville in 2018: "When a young woman was innocently killed [in Charlottesville],… [Trump] said 'they're are very find people on both sides.' No president has ever said anything remotely like that. So there’s this constant dog whistle and it bothers me a lot."

Editor's note: This article has been updated with new details throughout.