U.S. Deputy Attorney General Rod Rosenstein, who oversees the investigation by special counsel Robert Mueller into Russia's role in the 2016 presidential election, is set to meet President Donald Trump at the White House on Thursday to discuss his future.
The following explains what happens to oversight of the Mueller probe if Rosenstein is no longer in charge.
What is Rosenstein's involvement with the Mueller probe?
The deputy attorney general took charge of the investigation into Russian interference in the election because U.S. Attorney General Jeff Sessions, who had some contact with Russian officials while working on the Trump campaign, recused himself.
After Trump fired Federal Bureau of Investigation director James Comey in May 2017, Rosenstein appointed former FBI director Mueller to the role of special counsel and tasked him with investigating Russian interference in the election.
Rosenstein supervises Mueller and has signed off on his decisions to bring criminal charges against individuals associated with Trump's presidential campaign. The probe has so far resulted in more than 30 indictments and six guilty pleas.
Who would succeed Rosenstein in overseeing the Mueller probe?
If Rosenstein left his job, the task of overseeing Mueller's investigation would typically fall to the associate attorney general, the No. 3 official at the Department of Justice behind Sessions and Rosenstein.
The current holder of that position, Jesse Panuccio, does so in an acting capacity and has not been confirmed by the Senate.
That means under Justice Department rules he would not be able to succeed Rosenstein in taking charge of the special counsel probe.
Instead, it would fall to U.S. Solicitor General Noel Francisco, according to an internal Justice Department memo on succession from November 2016 that is still in effect.
Some legal experts have said Francisco would have to recuse himself because his former law firm, Jones Day, represented the Trump campaign. If that were to happen, the next in line to oversee the special counsel would be Steven Engel, the assistant attorney general in charge of the Justice Department's Office of Legal Counsel.
Could Trump pick a replacement for Rosenstein?
President Trump could potentially bypass the Justice Department's succession order by invoking the Vacancies Reform Act of 1998 (VRA), which lays out general rules for temporarily filling vacant executive branch positions when the prior holder "dies, resigns, or is otherwise unable to perform" their duties.
If Rosenstein resigned, the VRA would allow the president to replace him on an interim basis with another official who has already been confirmed by the Senate. That person could be from any part of the executive branch, not necessarily the Justice Department.
Some legal experts argue that such a replacement would not be able to oversee the Mueller probe because Rosenstein is doing so as acting attorney general. A Justice Department guideline holds that an official cannot be both acting attorney general and acting deputy attorney general, but experts differ on whether that rule would have to be followed.
It is also not clear whether the law, intended to address vacancies created by deaths or resignations, would apply if such a vacancy were created by an official being fired by the president. Such an appointment could be challenged in court on that ground.