WASHINGTON — President Trump’s weekend Twitter message asserting that former President Barack Obama had tapped his phones forced the White House into ever more verbal contortions on Thursday as aides struggled to defend the president’s charge.

In the latest iteration, the Justice Department declined to comment on whether Mr. Trump is — or is not — the subject of an investigation. “No comment,” a department official said.

In normal circumstances, a “no comment” from the Justice Department on the status of any investigation would be standard practice. And certainly there has never been any indication that Mr. Trump himself was the target of inquiries by the department and congressional intelligence committees into possible contacts between his associates and members of the Russian government.

But by venting his ire against Mr. Obama in a series of Twitter messages at dawn on Saturday, Mr. Trump awkwardly raised that possibility himself, since any wiretapping could have been the direct result of an investigation targeting him. One presidential tweet in particular — “how low has President Obama gone to tapp my phones during the very sacred election process” — clearly portrayed Mr. Trump as the victim of surveillance.