The long-awaited breakup between President Trump and Elon Musk was as personal and petty as anticipated, and yet it’s a sign of something much more than a conflict between two of the world’s most powerful and mercurial men.

It’s a signal that Mr. Trump is not finding it easy to hold his populist conservative coalition together.

At the beginning of the year, Mr. Trump’s coalition did not seem so vulnerable. To an extent unmatched since at least Ronald Reagan, it seemed as if Mr. Trump could enact a conservative agenda and find considerable support from the public. By raising tariffs on China, deporting undocumented immigrants, increasing oil production, cutting spending or fighting the “woke” left, he could stay on solid political ground.

Whether it’s because of his own limitations as a manager of competing players, the excesses of his own policies or the growing challenge of the national debt, it doesn’t appear to be so straightforward for Mr. Trump to hold the gang together.

The second Trump coalition is fraying

Mr. Trump won a second term with a much broader political coalition than the one that brought him to the presidency in 2016.

He added millions of young and nonwhite voters to his base of older, white, working-class populists and stalwart Republicans. He also added considerable support from anti-woke and anti-establishment elites who previously backed Democrats.