Biden vs. Trump: Live Updates for the 2020 Election

A full video of that conversation will be released at 10 a.m. on Thursday — a high-profile step by Mr. Obama to lend a hand to Mr. Biden, his former vice president. Hours ahead of the release, the Biden campaign put out another excerpt, this time on the subject of health care.

“I used to sit there and watch him in the bed and in pain and dying of glioblastoma,” Mr. Biden said of his older son, who died in 2015. “And I thought to myself, what would happen if his insurance company was able to come in, which they could have done before we passed Obamacare, and said: ‘You’ve outrun your insurance. You’ve outlived it. Suffer the last five months of your life in peace. You’re on your own.’”

Mr. Trump came into office on a promise to repeal the Affordable Care Act, but he and Republicans in Congress failed in their efforts to undo the health law in 2017. Still, the Trump administration has repeatedly sought to undermine the law, and it is now asking the Supreme Court to overturn it.

Health care was a central issue for Democrats in the 2018 midterm elections, and they are emphasizing it again this election cycle, especially with the pandemic underscoring the importance of insurance coverage and care for the sick.

“You and I both know what it’s like to have somebody you love get really sick, and in some cases to lose somebody,” Mr. Obama told Mr. Biden in their conversation. “But that loss is compounded when you see the stress on their faces, because they’re worried that they’re being a burden on their families. They’re worried about whether the insurance is going to cover the treatments that they need.”

He added: “I couldn’t be prouder of what we got done. Twenty million people have health insurance that didn’t have it because of what we did.”