Investing.com-- Elon Musk, the world’s richest man and a key White House advisor, appealed directly to President Donald Trump to reduce the severity of his trade tariffs, the Washington Post reported on Monday.

Musk had personally appealed  to Trump with his case, but was ultimately unsuccessful in changing the President’s mind, the Washington Post report said, citing two people familiar with the discussions.

Musk’s companies, specifically Tesla (NASDAQ: TSLA ), stand to be impacted by the tariffs. While Tesla does manufacture all of its U.S.-sold cars domestically, it still imports several components from China and other countries targeted by Trump’s tariffs.

Musk had over the weekend also made a series of social media posts criticizing top White House trade advisor Pete Navarro, while calling for a free trade zone between the U.S. and Europe.

Trump had last week unveiled sweeping, higher-than-expected trade tariffs against several major economies. China was among the worst-hit, with U.S. tariffs on Chinese goods now totalling about 54%.

Trump threatened to impose an additional 50% tariff on China if Beijing did not cooperate with his demands. But China’s Commerce Ministry decried Trump’s threats, warning that Beijing will “fight to the end” in the face of increased U.S. tariffs.

Trump’s tariffs on China are expected to spark severe supply chain disruptions for several major American companies, with Apple Inc (NASDAQ: AAPL ) seen among the worst hit by the new tariffs.

Trump’s tariffs are set to take effect from Wednesday.