Amid the fireworks of his spectacular breakup with Elon Musk last week was a striking admission by President Trump that once could have led to subpoenas.

As he lashed out at Mr. Musk for disloyalty, Mr. Trump threatened to cut off the billionaire’s federal contracts in retaliation, effectively acknowledging what his critics have long said, that he looks at the government as his personal instrument for dispensing favors to friends and penalizing those who cross him.

In the old days, that might have been cause for a corruption investigation. In the modern era, it’s just another Thursday. Mr. Trump has long since abandoned the kinds of rules and traditions that would constrain a president from employing the power of his office to personally steer federal contracts to allies and away from enemies. And even more remarkable, he has no hesitation about saying it out loud.

“The Musk quote is just further proof that Trump and the late King Louis share a common view of the world: The state, it is me,” said Trevor Potter, the president of the Campaign Legal Center and a former Republican chairman of the Federal Election Commission. “And yes, this is an example of Trump publicly and improperly threatening to use the enormous contracting power of the federal government as a weapon to punish someone for criticizing him. It is a complete abuse of power.”