WASHINGTON — Lawyers for the former F.B.I. deputy director Andrew G. McCabe, a frequent target of President Trump’s, have asked federal prosecutors whether a secret grand jury refused to indict him, which would be a sign that the government is struggling to make a case against him.

In a letter sent late Thursday, defense lawyers asked whether a grand jury had considered charges against Mr. McCabe, who is being investigated over whether he lied to internal investigators about interactions with the news media. The letter came shortly after the Justice Department told Mr. McCabe’s lawyers that it had rejected their pitch to the deputy attorney general to drop the case.

“It is clear that no indictment has been returned,” the lawyers wrote, citing coverage of the case by The New York Times and The Washington Post. A grand jury hearing evidence that was recalled on Thursday after months of inactivity left for the day without any sign of an indictment, The Post reported. None had emerged on Friday.

[Read the lawyers’ letter.]

The letter was the latest attempt by Mr. McCabe to stave off charges in the highly unusual and politically charged case. His lawyers have denied that he intentionally lied during an internal inquiry and have said that he is being singled out, noting that similar cases were typically handled administratively, not through criminal prosecution.