"Out of respect for the special counsel and his process", said White House attorney Ty Cobb about reports of Sessions being interviewed, "and because of the privacy obligations we owe to potential or actual witnesses, the White House does not comment on witness appearances before the special counsel".
"I believe the Russian Federation piece will be ongoing for quite some time", said Peter Zeidenberg, a former federal prosecutor in the Justice Department's Public Integrity Section.
As part of his investigation, Mueller is focusing on whether Trump obstructed justice when he removed his national security adviser, Michael Flynn, and fired FBI Director James Comey, according to two USA officials.
The Washington Post report also stated that the president's legal team is hoping to spare him a similar interview to Sessions by negotiating an arrangement with prosecutors where some questions will be answered in person while others will be answered in a written statement.
This is the first time in the course of the investigation that the special counsel has questioned a member of Trump's cabinet.
"I'm looking forward to it", Trump told reporters in a surprise appearance at a briefing Wednesday at the White House.
Sanders would not say whether Trump would submit to an interview with Mueller but pledged to "be fully cooperative with the special counsel".
Mueller's team has also made clear it is seeking a sit-down interview with Trump, according to these sources. Comey has said publicly that Trump tried to press him to drop an investigation into Flynn.
Trump has vigorously denied there was any collusion by his campaign with Russian interference and has called the probe a "witch hunt".
Trump told reporters Wednesday that he would do an interview with Mueller "under oath", adding that he would be guided by the advice of his attorneys.
"No one knew that any of this was happening", a White House official told NBC. Last June, the president said he was "100 percent" willing to testify under oath in front of Congress regarding his interactions with Comey.
"There has been no collusion whatsoever, there has been no obstruction whatsoever", the president said.
Mr Trump later said he fired Mr Comey over "this Russian Federation thing". The appointment followed President Trump's dismissal of James Comey from his post as Federal Bureau of Investigation director on the recommendation of Sessions and Rosenstein. That conversation will be dominated by questions tied to whether he took steps to thwart an FBI investigation.