Special counsel Robert Mueller's office interviewed Attorney General Jeff Sessions last week in connection with the investigation into Russian interference in the 2016 presidential election and now wants to question the president.

The Sessions interview came on the heels of the special counsel's reported questioning of fired FBI Director James Comey. In another major development, The Washington Post on Tuesday afternoon reported that Mueller is looking to question President Trump on his decision to fire Comey and Michael Flynn, his former national security adviser. The logistics of that interview remain unclear, as they will likely be negotiated between the special counsel and the president's legal team.

"Sessions may be in the single best position to either corroborate or impeach the credibility of folks that the special counsel might be looking at much more carefully," said Stephen Vladeck, a University of Texas law professor. "The president, Jared Kushner, Comey himself, who used to be Sessions's subordinate."

"Sessions is not the most important person in this investigation, but he may be the one with the most connections to it," Vladeck added.

The White House said that Comey's firing was driven by a recommendation from the Justice Department related to the FBI's handling of the investigation into former Secretary of State Hillary Clinton's use of a private email server. But Trump subsequently told NBC News's Lester Holt that he was going to fire Comey "regardless of recommendation," signaling that the Russia investigation figured into his decision-making.

The controversy surrounding Comey's ouster reached a peak last June, when the former FBI director testified publicly before senators on Capitol Hill that Trump had pressed him to stop the investigation into Flynn.

Flynn resigned in February after it was revealed he lied to senior administration officials about his conversations with then-Russian Ambassador Sergey Kislyak during the transition. He cut a deal with Mueller in December and is cooperating with the special counsel after pleading guilty to lying to FBI agents about his Russia contacts.

The New York Times reported Tuesday that the special counsel interviewed Comey last year, a meeting that focused on several memos written by the former FBI director chronicling his interactions with the president.

The special counsel's office declined to comment on the reported interview with Comey.

The interview with Sessions, a Trump surrogate throughout the campaign, is a sign that Mueller's probe is tightening on Trump's inner circle. Sessions is the first Cabinet member known to be interviewed in connection with the probe.

Sessions is also of interest to Mueller as he explores whether there was collusion between Trump's campaign and Moscow, given his high-level role on the campaign and interactions with Russians.

Sessions was forced to recuse himself from the Russia investigation last March amid scrutiny over his contacts with Kislyak, whom he met with twice during the campaign. Sessions received blowback on Capitol Hill for failing to disclose the meetings under oath during his confirmation hearing.

Since then, reports have emerged that Trump directed White House counsel Don McGahn to stop Sessions from recusing himself, efforts that were ultimately unsuccessful.

The Justice Department confirmed that the interview occurred last week. The interview is said to have lasted several hours.

Mueller has been given a broad mandate to probe Russian interference and any evidence of crimes arising from his investigation.

The probe has been a thorn in the side of the president, dogging his first year in office. Trump has repeatedly said there was no collusion during the campaign, describing the allegations as a "hoax" peddled by Democrats.

Meanwhile, the probe has also rankled Trump's Republican allies on Capitol Hill, who have recently stepped up charges of political bias on Mueller's team and at the FBI.

Trump insisted Tuesday he was not worried about what Sessions might have said during the interview, though he said he had not discussed it with the attorney general.

"I'm not at all concerned," Trump said.

The special counsel would only be able to compel Sessions to answer questions pursuant to a subpoena, legal experts say. Sessions is said to have voluntarily offered his testimony.

Mueller has already secured guilty pleas from Flynn and George Papadopoulos, a low-level campaign foreign policy adviser who admitted to lying to investigators about his Russia contacts.

Mueller has also indicted former campaign aides Paul Manafort and Richard Gates on charges of money laundering related to their work in Europe.

Sessions admitted to lawmakers in November that he recalled a 2016 interaction with Papadopoulos about the adviser's efforts to broker a meeting between the campaign and Russian officials, but said he did not remember it until reviewing Papadopoulos's account.

"I think a lot of it is going to be establishing timelines. Who knew what when," Vladeck said. "Who was in the room when various conversations took place."

Jordan Fabian contributed.