Washington (CNN) A former Senate aide charged with lying to the FBI has privately reached out to senators to seek their help in his criminal trial, raising the prospect that they may be subpoenaed to testify, Senate sources told CNN.

Members of the Senate Intelligence Committee have received letters from the legal team of the panel's former head of security, James Wolfe, asking if they would assist in his defense, either as a character witness or to help rebut the allegations made by federal authorities.

Whether any will cooperate is an open question. But if they refuse, it could prompt a legal fight over whether provisions under the "speech or debate" clause of the Constitution -- designed to protect lawmakers over Executive Branch interference -- could allow them to avoid taking the stand in what could be a messy criminal trial.

The issue did not come up at a Thursday status hearing, where US District Court Judge Ketanji B. Jackson instead denied a motion by Wolfe's attorneys that would have stopped President Donald Trump from making any more public comments about the case. Trump characterized Wolfe as a "very important leaker" immediately after the former aide's June arrest on charges that he lied to FBI agents about his interactions with the press.

Whether senators and reporters will be forced to take the stand is a matter bound to come up at future appearances. The judge set the next status hearing for August 23. After the trial date is set, senators and potentially reporters who were in contact with Wolfe could be hit with subpoenas.

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