Elon Musk has vowed to leave President Donald Trump’s advisory councils if the president pulls the U.S. out of the Paris climate accord. To many of Musk’s fans, it’s about time.

“Don’t know which way Paris will go, but I’ve done all I can” to convince Trump to stick with U.S. commitments made under his predecessor, Barack Obama, Musk wrote Wednesday in a post on Twitter. Asked what he’d do if Trump decides to leave, the chief executive said he “will have no choice but to depart councils.”

America’s clean-energy icon—the founder of Tesla Motors and SpaceX—angered many of his supporters earlier this year when he started meeting with Trump and joined the president’s business and manufacturing advisory councils. Some customers even canceled their $1,000 reservations for Tesla’s upcoming Model 3 electric car and posted their refunds on Twitter.

Musk continued to advise Trump even as Uber CEO Travis Kalanick succumbed to similar pressure to step down. Musk insisted that it was his chance to ensure the president was hearing from people who take the threat climate change seriously.

Now, as Trump nears a final decision on the Paris climate agreement, and appears to be leaning toward exiting, Musk seems to have reached the end of his patience. The accord was decades in the making, involving more than 200 nations representing almost the entirety of humanity.

The only nations that haven’t signed on are Nicaragua and Syria.

Other CEOs are mounting a last-minute push aimed at persuading the president. Tim Cook placed a call to the White House on Tuesday, according to a person familiar with the move. Twenty-five companies, including Intel and Microsoft, have signed on to a letter set to run as a full-page advertisement in the New York Times and Wall Street Journal on Thursday. A television ad ran Wednesday showed CEOs of top U.S. companies backing the pact.  

Before the November election, Musk tepidly criticized Trump, saying he was "probably not the right guy" for running the country. In December, he joined a council of 14 CEOs including Disney, Wal-Mart, and Uber. 

This article was provided by Bloomberg News.