"We have made significant progress from the debacle that was left by President Trump in his last term," Biden said.

Biden then went on to summarize some of his signature policies. On the economy, he vowed he will not raise taxes on anyone making under $400,000 a year and to continue his work to reduce health care costs, child care costs and give families financial breathing room.

"We're going to continue to fight to bring down inflation and give people a break," Biden said in closing.

The candidates were asked what they could do to help Americans battling the opioid crisis in the U.S.

After being prompted to respond to the question, Trump said that during his term as president they had "great equipment" and drug-detecting dogs to find illicit drugs at the border.

Biden said the U.S. needs machinery that can detect fentanyl and more agents at the border, and added that the U.S. is coming down "very hard" on countries in Asia that are producing fentanyl.

Moderator Dana Bash asked Biden, 81, and Trump, 78, to address voter concerns about their age.

"First of all, I spent half my career being criticized for being the youngest person in politics," Biden said. "I was the second youngest person ever elected to the United States Senate. And now I'm the oldest. This guy's three years younger and a lot less competent."

Biden said voters should look at his record and what his administration's accomplished.

Trump pointed to the "cognitive test" he's taken. In 2018, he took the Montreal Cognitive Assessment, a test designed to detect early signs of memory loss and other mild cognitive impairment.

"He took none," Trump said of Biden. "I'd like to see him take one, just one, a really easy one. Like go through the first five questions, he couldn't do it."

Biden had a poor start to this debate, and if he ends up being viewed as the "loser" tonight, he'd be just the latest incumbent president to go through this. Incumbent presidents like Ronald Reagan in 1984, George W. Bush in 2004, Barack Obama in 2012 and Trump in 2020 all lost 2 to 3 points in the polls after their first debate.

Reagan, the last president to face real questions about his age -- he was 73 in 1984 -- had a meandering performance that prompted questions about whether he had gotten too old for the job. Reagan shot back in the second debate against Democratic nominee Walter Mondale, who was in his mid-50s, with the famous line: "I will not make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent's youth and inexperience." Reagan, however, also had a roaring economy, which helped him win a landslide reelection victory.

-Geoffrey Skelley, 538