(Reuters) -Tesla CEO Elon Musk's polarizing political actions since acquiring Twitter, later rebranded X, in 2022 dramatically hurt the automaker's U.S. sales, underscoring how deeply its fortunes are intertwined with the billionaire's persona.

The findings quantify for the first time how the political actions of the world's wealthiest person - including his role in U.S. President Donald Trump's administration - may have cost Tesla billions in lost vehicle sales while benefiting rival electric carmakers.

Tesla's U.S. sales would have been between 67% and 83% higher, or about 1 million to 1.26 million additional vehicles, from October 2022 to April 2025, had it not been for what researchers call the "Musk partisan effect", according to a working paper from the National Bureau of Economic Research by Yale University economists.

Tesla did not immediately respond to a request for comment on the report.

As Democratic-leaning buyers shifted away from Tesla, that effect also boosted the sales of competitors' electric and hybrid vehicles by roughly 17% to 22%, the study found.

The Yale University researchers linked the drop to Musk's increasingly partisan behavior, including his roughly $300 million in donations to Republican candidates as well as leadership of the Department of Government Efficiency (DOGE) under Trump.

Musk's political stance has alienated environmentally minded Democratic buyers - historically Tesla's strongest base - according to surveys cited in the report.

Sentiment toward Tesla improved somewhat as Musk pivoted the company towards robotaxis, self-driving technology and robots in human form.

Tesla board Chair Robyn Denholm said in an interview with CNBC on Monday that the outside perception of Musk spending time in the U.S. government had diminished.

The NBER paper said Musk's actions also hampered California's progress toward its zero-emissions vehicle goals, concluding that the state would likely have met its 2026 targets "had it not been for the Musk partisan effect".

Registrations of Tesla cars in the state fell 9.4% in the third quarter, with its market share falling to 46.2% in the three-month period.