FRANKFURT (Reuters) -Investors called upon Porsche CEO Oliver Blume, who also heads parent company Volkswagen, to drop one of his roles on Wednesday as weakness in China and tariff-related challenges in the United States have forced the sportscar maker to cut its outlook.

Last month, Porsche said its margins had plunged in the first quarter and gave a more sombre forecast for the year due to a 42% drop in sales in China in the first three months of 2025, a slowing shift to electric cars and U.S. tariffs.

Blume faced frustrated investors at an annual shareholders meeting, with some criticising his decision to remain at the helm at both firms.

"Independent management of both groups is de facto not possible if one person manages both," said Hendrik Schmidt, expert for good corporate governance at Deutsche Bank unit DWS.

He said that the dual role was causing discounts on Porsche's share price.

Blume has in the past argued that his position was a recipe for success and would not last forever.

"Give up a position on the board at last," said Ingo Speich, head of sustainability at Deka Investment.

Porsche, which at its stock market debut in 2022 had a higher valuation than Volkswagen, has fallen out of favour and its shares have dropped about 45%.

Investors urged quick action in the face of Porsche's troubles in major markets China and the United States.

"Porsche is in a gruelling sandwich position between the trouble spots of China and the USA," Speich said, adding that the company had given no answers on how it planned to fix things in China.

"Porsche must become like its products: fast and powerful, yet safe and desirable," DWS's Schmidt said.

Speaking at the shareholder meeting, Blume acknowledged the challenges.

"Last year we had massive headwinds. Now we're experiencing a violent storm," he said, adding that the Chinese market had collapsed.

"It's perfectly clear to us: You expect more from Porsche. Of course. We do too," he said.

The investment funds cannot influence votes at the shareholders meeting as only non-voting preference shares are traded on the stock market. Parent company VW and Porsche Automobil Holding, the holding company of the Porsche and Piech families, have control.

(Reporting by Ilona Wissenbach; Writing by Madeline Chambers; Editing by Joe Bavier)