Exclusive poll: Biden won the debate convincingly

A new poll by Data for Progress provided exclusively to Vox shows that viewers thought Democratic nominee Joe Biden decisively won Tuesday’s first presidential debate against President Donald Trump, by a 52-39 margin.

The poll surveyed debate watchers but then weighted the demographics of the survey group to the population of likely voters in November. Most pollsters don’t do this, which ends up skewing their results toward Democrats because left-leaning college graduates are disproportionately likely to watch debates.

But even with the more Trump-friendly weighting, the poll shows a clear win for Biden and, not coincidentally, a fairly overwhelming sense that Biden’s conduct during the debate was more presidential.

When DFP asked about the actual policy exchanges during the debate, Biden’s performance was somewhat weaker than his topline numbers.

Respondents preferred Biden on nominating someone to the Supreme Court, for example, but did so by a relatively narrow 48-40 margin; he was also the winner on “the integrity of the election” by a 49-36 margin. Those are good numbers, but smaller than his wins on character questions:

Last but by no means least, on the question of which candidate came off as “more mentally sharp and stable,” Biden held a narrow lead. This is significant because the Trump campaign has spent months trying to portray the former vice president as over the hill.

Data for Progress also asked a series of questions regarding whether various moments from the debate are likely to influence voters’ decisions in November. On the economy, race and policing, Covid-19, candidates’ tone, and candidates’ style of communication, Biden was universally preferred.

Trump performed best when he spoke about the economy, where 34 percent of respondents said the back-and-forth made them more likely to support him versus 38 percent who said they were more likely to support Biden. The biggest gap in Biden’s favor came on the tone question, where Biden had a 42-34 edge — including advantages for Biden with white voters and male voters.

Historically, debates have only a modest influence on election outcomes. But as measured by this survey, Trump experienced essentially a top-to-bottom fiasco. He entered the debate behind, and he failed to pick up any support that might meaningfully help him on Election Day.