According to the survey, 11% of respondents considered Biden's victory "probably illegitimate", while 22% said it is "definitely illegitimate". Meanwhile, American opinions across the political spectrum have polarised considerably, with 71% of Republicans and 4% of Democrats not recognising Biden's election.
The poll also revealed that an overwhelming majority (91%) of Democrats considers Biden's victory either "definitely legitimate" (83%) or "probably legitimate" (8%), on the contrary, only 21% of Republicans recognise the current president.
"Given the continued questioning of Biden's victory by prominent Republican elected officials, conservative media personalities, and former President Trump, it is no surprise that 7 in 10 Republicans, conservatives, and Trump voters view the results of the 2020 election with scepticism, if not outright disbelief", director of the poll Tatishe Nteta said.
Nonetheless, the general opinion of Americans on the legitimacy of the 2020 presidential election has remained stable since April, with almost 6 out of 10 Americans considering Biden's victory legitimate, Nteta added.
The poll was conducted from 14-20 December, almost a year after the events of 6 January 2020, when the US Capitol was attacked by those protesting the outcome of the 2020 presidential election. The survey's organisers stressed that divisions in American society persist, including on the interpretation of those events and the need for penalties. While 86% of Democrats support continuing law enforcement efforts to investigate and prosecute the perpetrators of the Capitol attack, more than a half of Republicans opposed such measures.
The poll covered 1,000 people nationwide. The margin of error was 3.1%.