(The Center Square) – Elon Musk, the tech billionaire who founded Tesla and SpaceX, made one simple request at former President Donald Trump’s campaign rally on Saturday.

Register to vote – and then actually cast a ballot on Election Day.

“President Trump must win to preserve the Constitution,” Musk said to the crowd gathered in Butler, about 45 minutes north of Pittsburgh. “He must win to preserve democracy and America. This is a must-win situation. A must win.”

Musk, donning a black "Make America Great Again" hat, bounced onto the stage with a smile after Trump, midway through his speech, invited him to the podium. The strange bedfellows recently made headlines after deploying Starlink, Musk’s satellite broadband internet service, to hurricane-ravaged North Carolina earlier this week.

Musk’s support for Trump, however, isn’t as recent. His first endorsement came an hour after the Republican candidate survived the attempted assassination in Butler.

“The true test of someone’s character is how they behave under fire, and we had one president who couldn’t climb a flight of stairs and another who was fist pumping after getting shot,” Musk said. “Fight! Fight! Fight!”

The chant harkens back to the moment Trump, face bloodied, raised his fist into the air as Secret Service agents shuffled him off stage, an American flag draped behind him.

The moment was an about-face for Musk, who said in March he wouldn’t donate to either presidential candidate. Since then, he’s donated to the U.S. House Republican’s fundraising arm and created a political action committee, America PAC, to help fund Trump’s campaign.