WASHINGTON — When Donald J. Trump descended on the capital Friday, he was expected to finally concede that the racially tinged falsehood he had gleefully propagated, that President Obama was born outside of the United States, had in fact been a lie.

But before Mr. Trump got around to what was a grudging and terse admission, which itself included a falsehood about the provenance of so-called birtherism, he had some business to tend to.

“Nice hotel,” said Mr. Trump, the Republican nominee for president, delighting in his newest property and the opportunity to plug it free on live television. He was holding his news conference at his new hotel in the Old Post Office building on Pennsylvania Avenue, which, he promised, is “going to be something very special.”

He seemed untroubled in using an ostensible campaign event just a few blocks from the White House to openly promote his personal commercial interests 52 days before the election.