President Donald Trump and his challenger Joe Biden have fiercely clashed in one of the most chaotic and rancorous White House debates in years.
Amid angry shouting and name calling, the two fought over the pandemic, white supremacy and the economy during the 90-minute forum in Cleveland, Ohio.
Mr Biden called the president a "clown" and told him to "shut up". Mr Trump brought up drug use by his rival's son.
Opinion polls suggest Mr Biden has a steady single-digit lead over Mr Trump.
But with 35 days until election day, surveys from several important states show a closer contest.
Polls also suggest one in 10 Americans have yet to make up their mind who to vote for. But analysts said Tuesday night's debate - the first of three - probably would not make much difference.