The Affordable Care Act, and Trump’s push to repeal it, become a focus at the Democratic convention.

Amid a pandemic that has highlighted the importance of medical care even as millions of Americans who lost their jobs also lost their insurance, some of the most emotionally resonant moments of the second night of the Democratic convention came in discussions of health care.

It is an issue that Joseph R. Biden Jr. has sought to lay claim to, by invoking both his fight alongside President Barack Obama to pass the Affordable Care Act and his own history dealing with suffering and loss.

One segment showed the candidate listening as supporters described their ordeals in the health care system.

The father of a 4-year-old boy in Arizona talked about how his son’s heart transplant was covered by the Affordable Care Act. A former longtime Republican voter, Jeff Jeans, described putting off seeing a doctor for his laryngitis because he was uninsured, only to find out that he had cancer. He said that he signed up for coverage under the act and “that same day, they started my chemo and radiation, and it saved my life.”