A battle over what President Donald Trump's former chief strategist can tell Congress has thrown a glaring spotlight on the potential conflicts of interest surrounding White House Counsel Don McGahn and how long he will remain in that job.

McGahn's office was deeply involved in instructing Steve Bannon on which questions from the House Intelligence panel's Russia probe he shouldn't answer, according to a person familiar with the matter. But McGahn was interviewed by investigators for Special Counsel Robert Mueller looking into Russian election meddling -- and he shares a lawyer with Bannon.

As the White House's top lawyer, McGahn defends the Office of the President, not Trump himself. But former prosecutors say that his loyalties could be divided given his personal position as a witness to episodes under investigation by Mueller and Congress.

Bannon's appearance on Capitol Hill this week was the clearest illustration yet of the complications stemming from the overlapping sets of witnesses and lawyers in the multiple Trump investigations. Over the course of more than nine hours Tuesday, Bannon's testimony was interrupted several times so that his lawyer, William Burck, could call the White House to ask whether he could answer certain kinds of questions, according to a person familiar with the matter.

The White House lawyer on the other end of the phone was Uttam Dhillon, an associate counsel in McGahn's office. Dhillon asked Burck to instruct Bannon to decline to answer, citing the possibility that the White House may want to invoke executive privilege in the future, the person said.

Newsletter signup for email alerts

It's unclear whether McGahn was involved in the decision and the White House declined to comment. Even so, the request was conveyed through Burck -- who is representing Bannon and McGahn. In effect, McGahn's personal lawyer was conveying a legal request from McGahn's White House shop to a fellow client of McGahn's lawyer.

Burck, of Quinn Emanuel Urquhart & Sullivan LLP in Washington, also represents ex-White House chief of staff Reince Priebus. Burck declined to comment on the potential for conflicts.

One senior Trump aide disputed the exact role the White House played in Bannon's testimony. White House Chief of Staff John Kelly said during an interview with Fox News on Wednesday that the White House didn't urge Bannon to invoke executive privilege.

"Steve has had very, very little contact with the White House since he left," aside from a few phone calls, Kelly said.

The House Intelligence Committee had asked Bannon to return as early as Thursday to answer their remaining questions, but he won't be appearing Thursday, said a person familiar with Bannon and his legal team. White House lawyers are unlikely to change their minds about instructing Bannon not to answer the committee's questions about his time working on the presidential transition team or in the White House, a person familiar with the matter said.

Hanging over this fight is McGahn, who continues to run the White House legal office while remaining a key witness -- and facing potential legal exposure himself -- in a criminal investigation. McGahn has been interviewed in December as part of Mueller's probe, according to a person familiar with the matter.

Democrats on the House Intelligence Committee also want McGahn to testify. "He's on our list," said Rep. Adam Schiff of California, the panel's top Democrat.

"McGahn's job is to minimize the political harm to the White House," said Peter Zeidenberg, a former federal prosecutor and now a partner at Arent Fox LLP. "He just has to do it ethically. He's not doing his job if he's not trying to keep them out of hot water."

McGahn isn't involved in responding to inquiries from the Mueller's investigation, leaving those to Ty Cobb, a different White House lawyer who reports separately to Trump. But McGahn's office is directly involved in coordinating with the congressional inquiries.

The White House counsel advises the Office of the President on legal issues while also handling a variety of administrative tasks, such as overseeing executive and judicial nominees and presidential pardons.

Court rulings stemming from investigations of former presidents Richard Nixon and Bill Clinton made clear that the White House counsel's job is to defend the office and not the person who occupies it, which is why Trump has hired separate personal lawyers to represent him in Mueller's investigation.

McGahn was Trump's chief lawyer during the campaign and has had a front-row seat to many of the controversies Mueller is investigating. He was the first person in the White House to be alerted by the Justice Department that then-national security adviser Michael Flynn could be compromised by the Russians. That meeting was followed by an 18-day period before Flynn's firing, a gap that Mueller will likely want to fill in.

McGahn later had a prominent role in the firing of FBI Director James Comey, advising Trump against sending a termination letter described by a person who had seen it as emotional, impolite, and provocative. McGahn's recollection of Trump's thinking at the time could be grist for determining whether Comey's departure was tied to a refusal to drop the Flynn probe.

When it comes to Burck representing three figures involved in the Trump probes, it's not unusual for an attorney to have several clients in the same matter, as long as the clients agree their interests are served. Such agreements may be severed in the event the clients end up in a position to testify against each other.

"The White House counsel has a big, crucially important job. It does not include helping different witnesses in the same investigation to keep their stories straight," said Nicholas Allard, dean of Brooklyn Law School.

"I would think any lawyer would have their hands full with any one of those clients," Allard said of Burck's representation of Bannon, McGahn and Priebus. "And it could be extraordinarily difficult for even the most outstanding lawyer to avoid conflicts not to mention ethical peril. The lawyer's obligations of professional conduct require more than helping them keep their stories straight."

Mueller subpoenaed Bannon to testify before a grand jury after remarks attributed to him appeared in "Fire and Fury: Inside the Trump White House" by Michael Wolff, a person familiar with the matter said.

Bannon agreed to sit down with Mueller later this month, though a date has not yet been set, according to the person, who discussed the situation on condition of anonymity. Bannon doesn't plan to invoke executive privilege when he meets with Mueller, the person added.

If Mueller doesn't raise any objections to Burck's role representing the trio, it's a signal he doesn't intend to prosecute any of the three men, said Sol Wisenberg, a white collar defense lawyer in Washington.

Mueller has already challenged some of the lawyering in the prosecution of former Trump campaign chairman Paul Manafort and his one-time associate Richard Gates. Before both men were indicted in October, Mueller won a court ruling that forced a lawyer for the two to testify before the grand jury, rejecting her claims of attorney-client privilege.

As he did with Gates after his indictment, Mueller could assert that Burck's multiple representations pose a conflict of interest.

In November, Mueller and the Justice Department asked judges to review a potential conflict of interest involving a lawyer for Gates, who is accused of money laundering with Manafort. The lawyer also represents a California man accused of fraud and who has a longstanding personal and business relationship with Gates.

After questioning Gates and the California defendant, the judges determined that the lawyer could represent both men.

Author information: Bloomberg contributors: Shannon Pettypiece, Billy House and Jennifer Jacobs.