Hurricane Harvey was the rarest of disasters to strike during the Trump presidency — a maelstrom not of Mr. Trump’s making, and one that offers him an opportunity to recapture some of the unifying power of his office he has squandered in recent weeks.

Now a tropical storm as it continues to inundate the Texas and Louisiana coasts, Harvey is foremost a human disaster, a stop-motion catastrophe that has already claimed at least 10 lives and destroyed thousands of structures. But hurricanes in the post-Katrina era are also political events, benchmarks by which a president’s abilities are measured.

Mr. Trump is behaving like a man whose future depends on getting this right.

The president will visit Corpus Christi on the Texas gulf coast on Tuesday, as Harvey regains strength and hurtles toward Louisiana. The visit, aides say, is intended to highlight his commitment to coordinating long- and short-term federal responses with local officials. During a White House news conference on Monday afternoon, Mr. Trump announced that he planned to make a second trip to the region, as early as Saturday. That one to Texas and to Louisiana.

In announcing his trips, he used the dulcet, reassuring and uplifting language of prior presidents. His rhetoric was strikingly different from his much-criticized pronouncements at a news conference this month when he equated the actions of leftist protesters in Charlottesville, Va., with the violent, torch-wielding alt-right activists who hurled anti-Semitic and racist epithets.