Donald J. Trump has praised Hungary’s prime minister, Viktor Orban, for his leadership of Turkey, and confused Nikki Haley and Nancy Pelosi. President Biden has named dead former European leaders when describing his contemporary peers, and referred to Egypt as Mexico.
The episodes might have raised parallel concerns about age and mental acuity. Instead, while Mr. Biden, 81, has been increasingly dogged by doubts and concerns about his advancing years from voters, Mr. Trump, who is 77, has not felt the same political blowback.
The response suggests profound differences not only between the two men, but in how they are perceived by the American public, and in what their supporters expect of them — a divide that could play a major role in the coming presidential election.
In a New York Times/Siena College poll of six battleground states, an overwhelming majority of voters said they had serious concerns about Mr. Biden’s age, with 70 percent saying he is too old to be president. Fewer than half of voters have expressed similar misgivings about Mr. Trump.
“Even though we know both candidates are three and a half years apart, one side seems to have it sticking a little more, and that’s going to be a concern,” said Representative Mark Pocan, Democrat of Wisconsin.
Some of it comes down to basic physical differences.
Mr. Biden’s voice has grown softer and raspier, his hair thinner and whiter. He is tall and trim but moves more tentatively than he did as a candidate in 2019 and 2020, often holding his upper body stiff, adding to an impression of frailty. And he has had spills in the public eye: falling off a bicycle, tripping over a sandbag.