That remark came after revelations that Sessions had met with Russia's ambassador to the USA last year, despite testifying under oath during a confirmation hearing that he "did not have communications with the Russians". Sessions is especially important to the case because as the attorney general, he was Comey's boss, and because Comey testified "the attorney general lingered by my chair, but the president thanked him and said he wanted to speak only with me".
In testimony last week, Mr Comey suggested Mr Trump had fired him to undermine the Russian Federation inquiry.
Comey said Trump told Sessions and other administration officials to leave the room before Trump asked him in February to drop a probe into former National Security Adviser Michael Flynn's contacts with Russian Federation.
Former FBI Director Comey testified last week that he made records of his interactions with the president because he felt the president might one day lie about those interactions.
Comey also testified that later, he implored "the attorney general to prevent any future direct communication between the president and me".
Was he aware the president had chose to fire Comey before seeing that memo - and did he ask the DOJ to prepare that memo for him? Sessions removed himself from involvement any probe into alleged Russian meddling in the elections in March, but maintained he did nothing wrong by failing to disclose that he met a year ago with Russia's ambassador.
As the White House's political crisis over the Russian Federation investigation has grown, the attorney general has laid low.
But, in contrast to Comey's detailed account, it is unclear to what extent Sessions will be willing or able to answer the committee's questions, with the possibility that he might invoke executive privilege on some key matters.
The announcement caps the drama that started over the weekend when Sessions canceled two appearances Tuesday, citing former Comey's blistering testimony last week. The matter is also being investigated by several congressional panels, including the Senate Intelligence Committee. Deputy Attorney General Rod Rosenstein will attend that hearing in his place, and Sessions will go before the Senate Intelligence Committee.
Late Monday morning, Senator Richard Burr, a North Carolina Republican, and Senator Mark R. Warner, a Virginia Democrat, announced that the hearing would be public.
According to Comey's testimony: "The last person to leave was Jared Kushner, who also stood by my chair and exchanged pleasantries with me".
Sessions, an early supporter of Trump's election campaign, will be the most senior government official to testify to the committee on the Russian Federation issue, which has dogged the Republican president's early months in office.
Lawmakers, including Al Franken of Minnesota and Patrick Leahy of Vermont, have asked the FBI to investigate and to determine if Sessions committed perjury when he denied having had meetings with Russians.
In a separate development Monday, Trump held his first Cabinet meeting with everyone on board. "We've obviously pressed the White House", he said. Recent news reports have said Sessions offered to resign just weeks ago, saying he needed to be given "the freedom" to do his job. But one by one, pretty much everyone else seated around the table took the opportunity to lavish their leader with praise, too, as the media looked on.
A third participant in that meeting, White House senior adviser and Trump's son-in-law Jared Kushner volunteered in March to testify before the intelligence committee. Also certain to be of interest is Comey's claim that Sessions "lingered" by Comey's side when the president ordered the room cleared and what Sessions thought when the president then directed him to leave. Melania Trump said in a Twitter message.