Partisan voters question the other guy’s mental fitness

August 28, 2020, 7:00 PM UTC

Donald Trump claims that Joe Biden is “mentally shot.” Do voters agree? Polling conducted by YouGov for Yahoo News shows that while Biden has an advantage on this issue, views are driven by partisanship.

Biden supporters overwhelmingly reject challenges to Biden’s mental fitness. Trump supporters overwhelmingly accept them.

During August’s Democratic convention, the Trump campaign escalated the argument, launching a digital attack ad, “What Happened to Joe Biden?,” that highlighted clips of him stumbling over words during the 2020 campaign. But after the convention, many pundits were convinced Trump’s attack had “backfired.” Biden’s convention speech, they said, “made it a lot harder for Republicans to tag him ‘Slow Joe’” and “blew a hole” in the notion that he is “mentally shot.”

Did it? The survey data tells a more nuanced story. Biden certainly comes out of his convention with an advantage on mental fitness. In the Yahoo News/YouGov poll conducted the weekend following the Democratic convention, more registered voters agree that the former Vice President has “the mental ability a president needs” (47%) than say the same for Trump (39%). The difference is bigger on the negative side: Far more reject the notion that Trump is mentally fit (55%) than do the same for Biden (40%).
While Biden has an advantage on this issue, the degree of partisan polarization is striking. Four out of five Democrats (82%) agree that Biden is mentally fit (only 6% disagree), while even more (88%) reject the notion that Trump is mentally fit. Among Republicans, the numbers are essentially reversed – 84 percent consider Trump mentally fit (and 11% disagree), while 81 percent consider Biden unfit. 

The polarization by candidate support is even more pronounced: The share of Biden supporters who consider their candidate mentally fit (86%) is exactly the same as the number of Trump supporters who consider Biden unfit. The same thing happens for Trump: Exactly the same percentage of his backers consider him mentally fit (92%) as Biden supporters consider Trump unfit.

Biden’s has an overall advantage on this question because he has more supporters than Trump – and because among independents, Trump’s unfitness score (61%) is higher than Biden’s (50%). 

The pattern is similar to that of a question which asks about the broader notion of candidate intelligence. Voters are more likely to describe Biden as intelligent (39%) than to apply that description to Trump (32%). Again, the partisan and candidate support polarization is immense. Two-thirds of Democrats (66%) describe Biden as intelligent, while only 5 percent say the same for Trump. The Republican response is a mirror image – 67 percent describe Trump as intelligent compared to 9 percent willing to say the same for Biden.
If there is one thing voters of both parties agree on, it’s that “intelligence” is an important leadership quality in a president. Nearly as many Republicans (82%) as Independents (84%) and Democrats say intelligence is a very important leadership quality in a president right now. Overall, intelligence ranks near the top in importance of eight qualities tested, with an overall very important score among all registered voters (83%) within a point of competence (84%) and taking responsibility (82%). The difference is that partisan polarization shapes voter perceptions of candidate qualities and traits.

These questions cannot definitively resolve whether perceptions of Biden’s mental fitness for office improved during the Democratic convention, because they were asked for the first time in the most recent survey. However, Biden’s eight percentage point advantage over Trump on perceptions of mental fitness among all registered voters (47% vs 39%), is similar to a similar question asked on a Monmouth University national poll of adults in July. They give Biden a seven-point advantage in having “the mental and physical stamina necessary to carry out the job of president” (52% are confident in Biden on this issue vs 45% confident in Trump).

When combined with the pattern of polarization and the lack of movement in voter preferences in recent weeks suggests that Trump’s assault on Biden’s mental fitness has changed few, if any, minds.

See the toplines and crosstabs from this week’s Yahoo News/YouGov Poll 

Methodology
: The Yahoo News survey was conducted by YouGov using a nationally representative sample of 1,145 U.S. adult residents interviewed online Aug. 21-23, 2020. The respondents all participated in a prior Yahoo News survey conducted Aug. 14-15, 2020, and were contacted to participate. Of the 1,529 adults in the Aug. 14-15 survey, 1,145 responded to this survey — a recontact rate of 74.9 percent. Respondents were re-interviewed from the previous nationally representative survey. The sample was weighted according to gender, age, race, education, geographic region, news interest, 2016 presidential vote and registration status, and baseline vote intention of the first wave. The margin of error is approximately 4 percent.