Sessions is likely to face questions by the Senate Intelligence Committee over his dealings with Russian officials during the campaign and whether he had a role in firing former FBI Director James Comey, who testified last week before the same panel.
Sessions is prepared to make clear that there was no "third meeting" with Russian Ambassador Sergey Kislyak at the Mayflower Hotel, the source said, pushing back on reports that Sessions could have met with Kislyak at an April 2016 Trump campaign event they both attended at the hotel.
Sessions is scheduled to testify from 2:30 p.m. (1830GMT) on Tuesday.
Comey's testimony on Thursday also raised new questions about the attorney general's relationship with Russian officials with ties to President Vladimir Putin.
James Comey was in his New Jersey hometown of Allendale with his father on Sunday, days after testifying before a Senate panel on his meetings with Trump. The attorneys general of DC and Maryland will file a lawsuit later today against President Trump, alleging he violated the Constitution by allowing his businesses to accept payments from foreign governments. The matter has dogged the Republican president's early months in office.
The committee announced on Monday the hearing will be public as was demanded by Sessions.
At a press conference on Friday, Trump denied Comey's account that he asked Comey to pledge allegiance or he asked the then FBI director to drop the investigation into former National Security Advisor Michael Flynn. But Comey believed that he was sacked because of his investigation into Russia's ties to the Trump campaign.
Comey testified that the FBI investigation into possible collusion between Russian Federation and the Trump campaign did not extend to Trump himself during the time Comey was leading the FBI. The attorney general may also face questions on that. "So I' m inviting him to come testify, and we could work that out", Schumer said, adding they would also consult with Robert Mueller, the special counsel to oversee the probe into the Trump campaign's relations with Russian Federation, before the hearing.
Sessions had been set to testify before a budget-related subcommittee on Tuesday but, in letters to key lawmakers, said the intelligence committee that heard from Comey would be the more appropriate venue considering the Russia-related questions.
The report notes that the Secret Service has "handled recording systems within the White House for past presidents, including presidents Richard Nixon and John F. Kennedy".