President Trump on Sunday said on social media that the Lincoln Memorial Reflecting Pool’s problems were caused in part by “some contractor error done by rushing the job for a July 4th opening.” It was a change in rhetoric for the president, who had spent weeks falsely blaming the pool’s problems on vandals.

The Trump administration’s efforts to rush through repairs to the pool, a national landmark, ended in disaster earlier this year. A hastily installed blue lining began to peel up, and new water-purification systems failed to prevent a huge bloom of algae that turned the pool green.

Mr. Trump responded to the tears in the blue lining with falsehoods, saying that it had been slashed by vandals. The U.S. attorney in Washington, Jeanine Pirro, charged at least seven people with vandalizing the pool, then dropped at least some of the cases after she discovered that the repair job had failed on its own, she said.

In his social media post, Mr. Trump also conceded that there was “no video or proof” to back up the assertions that vandalism damaged the pool. Still, he continued to blame one of the people who had been charged with vandalism, David Hearn, a former U.S. Olympian. Mr. Hearn had been charged with a felony by Ms. Pirro’s office, before his case was dropped.

The pool remains drained for repairs. In his post, Mr. Trump said that “We are working on the Pool, and it will reopen shortly.”