Special Counsel Robert Mueller has reportedly told lawyers representing Donald Trump that he could issue a subpoena for the US president to appear before a grand jury.
The Washington Post, citing four people familiar with a meeting between Mueller and Trump's lawyers in March, reported that the special counsel raised the prospect of a subpoena during a meeting in March after the president's team said he was under no obligation to talk to investigators.
Who is Robert Mueller? Mueller is a lawyer and former Marine who headed the FBI under presidents George W. Bush and Barack Obama.
What is he investigating? Mueller is leading a probe into alleged Russian interference in the 2016 US presidential election, whether Trump campaign figures were involved, and any other matters that arise from the investigation. He was appointed in May 2017.
What are his powers? Mueller can subpoena records, bring criminal charges and prosecute anyone who interferes in the investigation. Only Deputy Attorney General Rod Rosenstein, who appointed Mueller, has the power to fire him.
John Dowd, who left Trump's legal team shortly after the March meeting, subsequently confirmed in an interview with Reuters that Mueller had raised the possibility of a subpoena. "This isn't some game. You are screwing with the work of the president of the United States," Dowd reportedly told the investigators.
If Trump were to refuse to voluntarily sit down for an interview and Mueller issued a subpoena, the issue could go to the Supreme Court. The president's new legal team, which includes former New York mayor Rudy Giuliani, is reportedly considering how to respond to requests for a formal interview.
49 questions for Trump
The news follows the leak of a series of subjects that the special counsel, who is looking into alleged Russian meddling in the 2016 US presidential election and possible collusion between the Trump campaign and Russia, wants to ask Trump about in a formal interview.
The list was obtained and published by the New York Times. Trump hit out at the "disgraceful" leak later in the day, although it remains unclear who released the 49 questions to the media. The newspaper said it obtained them from someone outside Trump's legal team.
"It's hard for me to imagine it's coming from Mueller's team," Savannah Law School professor Andrew Wright told Reuters. "And it's kind of a ham-handed effort if it's someone who's trying to help the president."
What are the questions?
The Washington Post reported on Wednesday that Mueller's team told Trump's lawyers of 16 subjects they were interested in asking the president about, and Trump lawyer Jay Sekulow subsequently drew up the list of 49 questions.
The subjects indicate the breadth of the Mueller investigation, but are unlikely to reflect a full breakdown of the scope or angle of questions the special counsel would ask.
The questions compiled by Sekulow address Trump's firing of James Comey as FBI director, the role of former national security adviser Michael Flynn, the president's relationship with Attorney General Jeff Sessions and the infamous "Trump Tower meeting" in 2016 between campaign officials and Russian citizens.
They also cover the president's business interests, possible dealings with Russia, his trip to Moscow in 2013 for the Miss Universe pageant, and his relationship with former campaign chair Paul Manafort.
Russia has denied interfering in the 2016 US presidential election, and Trump has denied there was any collusion between his campaign and Moscow.