Some have accused Arizona’s Doug Ducey of mocking the Democrat candidate, who has a speech impediment, after a video of the incident was shared on Twitter by the New York Times correspondent Maggie Haberman.
In the video, Mr Ducey can be heard saying: “J-J-Joe Biden is wrong for America!” while Mr Trump is stood to the side, waiting to approach the microphone.
Haberman’s tweet, which has now been deleted, read: “The governor of Arizona mocks Biden’s stutter, almost certain to become the latest person to claim he didn’t know when asked about it.”
Haberman later clarified that she deleted the tweet because it was not entirely clear whether Mr Ducey was indeed mocking Joe Biden, or if it was a “reverb” sound malfunction.
Mr Ducey has also responded, tweeting to Haberman: “This is false. I did not mock Joe Biden's stutter, nor would I ever.”
Twitter users remain divided on the topic, some suggesting Haberman was being too “tentative” in taking the video down, while others said they had been following Mr Ducey for years and felt such mockery would be out of character.
The allegation involving Mr Ducey comes after a Republican senator was accused of racism for making fun of Kamala Harris’s name at another Trump rally.
David Perdue, a senator from Georgia and the brother of the secretary of agriculture, appeared to intentionally stumble as he said the Democrat’s first name as he warmed up the president’s crowd in the city of Macon.
Claiming that Mr Trump’s challengers, Joe Biden and Kamala Harris, would bring “radical socialism” to the nation if they win in November, he then mispronounced “Kamala”.
“Kamala? Kamala? Kamala-mala-mala,” he said, as the crowd laughed. “I don’t know. Whatever.”