Tesla's first-quarter sales slumped 13%, its weakest performance in nearly three years, as backlash to CEO Elon Musk's embrace of far-right politics grows and as consumers seek out newer models from rival electric-vehicle makers.

Mr. Musk’s involvement in right-wing politics contributed to a 13% drop in deliveries in the first quarter, including steep declines in E.V.-friendly places like Norway.

Tesla sales fell 13% in the first three months of the year, another sign that Elon Musk’s once high-flying electric car company is struggling to attract buyers. The double-digit drop is likely due to a combination of factors,