Sales fell to 384,122 in April through June, down from 443,956 in the same three months last year.
During the latest period, Musk formally left the Trump administration as a cost-cutting czar, and hopes rose that sales would recover. The Tesla CEO himself recently said the company was in the midst of a "major rebound" in sales, a statement contradicted by the latest figures.
Still, some parts of the report were encouraging. Sales of the Models 3 and Y totaled 373,728, above the estimate of 356,000 from Wall Street analysts. Tesla shares rose 5% on the news.
“The numbers weren’t as bad as thought with all the analyst forecast cuts we saw over the past week,” said Morningstar's Seth Goldstein, though he added the report overall showed the company faces big challenges. “The current product lineup is at market saturation and Tesla will need the new affordable vehicle to grow deliveries.”
Musk has promised a cheaper EV model would be coming this year that would boost sales.
It's not clear yet if Musk's latest feud with Trump will help lure back buyers who have been angry at the billionaire's political positions. After Musk once again took to social media to criticize Trump's budget bill, the president threatened Tuesday to use the power of his office to hurt his companies, including Tesla, pushing its stock down more than 5%.
A June AP-NORC poll showed about half of U.S. adults have an unfavorable opinion of Tesla, including 30% of Republicans.
The new figures come as Tesla is focusing less on new models and more on robots, self-driving technology and robotaxis ferrying passengers around without anyone behind the wheel.
Tesla is in the midst of a test run of robotaxis in Austin, Texas, that seems to have gone smoothly for the most part. But it also has drawn the scrutiny of federal car safety regulators because of a few mishaps, including one case in which a Tesla cab was shown on a video heading down an opposing lane.
The competition from rival EV makers is especially fierce in Europe where China's BYD has taken a bite out of its market share. Tesla sales fell 28% in May in 30 European countries even as the overall market for electric vehicles expanded sharply, according to the European Automobile Manufacturers' Association.
Musk has acknowledged that his work as head of the Department of Government Efficiency and his embrace of European far-right candidates have hurt the company. But he said earlier this year that much of the sales plunge is due to customers holding off while they waited for an ugrade to Tesla's best selling Model Y. That new version has been out for months now.
Tesla reports second quarter financial results on July 23. In the first quarter, net income fell 71%.