About 81% of debate watchers say it didn't influence their choice of president.

An additional 14% said it made them think about it but didn't change their mind, and 5% said it changed their mind about whom to vote for.

Roughly equal shares of Joe Biden and Donald Trump supporters said the debate changed their minds.

Biden's support fell slightly after the debate, with 31% viewing him favorably, compared with 37% in a survey of the same voters conducted before the debate.

As for Trump, his share of supporters rose to 43%, up from 40% of observers before the debate.

About 48% of debate watchers say Trump has better assuaged concerns about his ability to handle the presidency. 23% of observers said Biden did better, while 22% said neither candidate did. Another 7% thought both candidates did equally well.

About 48% of debate watchers said they would vote only for Trump, 40% said they would vote only for Biden, 2% said they were considering both candidates, and 11% said they were not considering voting.

• U.S. presidential candidates Joseph Biden and Donald Trump had their first debate on June 27. In particular, they talked about Ukraine.