Mr. Musk dug into his companies’ budgets, preferring to cut too much rather than too little and to deal with the fallout later. Under Donald Trump, he is set to apply those tactics to the U.S. government.

The Biden administration is playing it smart, laying the groundwork to protect clean energy programs from a potential rollback under Trump. By finalizing a wave of loans and grants for clean energy before year-end, they're effectively locking in incentives, making it far harder for a new administration to undo them come January.